This allow to use standalone slapos with some requests being forwarded
to another slapos master. The intended use case is to make have frontend
requests forwarded to "real" slapos master when embedding slapos in
theia or slaprunner.

In SlapOS, both users or partitions can requests partitions. With the
multimaster support of slapos proxy, all requests where made as a user,
but in the case of recursive slapos - where a partition from the "outer"
slapos includes an "inner" slapos, it makes sense to forward partitions
requests as the partition in the "outer" slapos - this way when this
partition is destroyed all partitions that might have been requested are
also destroyed.

To request as partition, the multi-master entry must define two extra
keys:
 - computer, that can be optained by $${slap-configuration:computer}
from instance buildout
 - partition, that can be optained by $${slap-configuration:partition}

When these are not set, the request will be made as a user, like it was
the case before.

We also change the test to unset SLAPGRID_INSTANCE_ROOT because this
implementation has side effect - the environment variable is set and
never unset. Without this, test fail when running the full test suite
because a previous test was leaking SLAPGRID_INSTANCE_ROOT. This is
definitely something we'll have to improve later.

Eventhough implementation might be a bit more efficient is we use the
low level API, we probably don't need performance here and it's easier
to use the request API

revert accidentally pushed commit and fix test failures introduced by nexedi/slapos.core!192

See merge request !216

fixup 31864c5c to make test pass

This reverts commit 3160c589.

pushed by mistake. This is unfinished but it was wrong because we copy
this log file to snapshot directory before we are done writing to it.

When we recurse in instance to find nested slapos that might be using
parts from ourselves, we check all files named slapos.cfg but we may
encounter some slapos.cfg that are not actual slapos config files, for
example in testnodes we have a working copy of slapos repository which
contains a stack/slapos.cfg which is completly different.

This was breaking prune with an error like this:

    2020-04-29 20:07:28 slapos[2097] DEBUG Reading config at /srv/slapgrid/slappart9/srv/testnode/czp/slapos-repository/stack/slapos.cfg
    2020-04-29 20:07:28 slapos[2097] ERROR No section: 'slapos'

See merge request !211

`FolderSizeSnapshot` is too slow and cause some "Database is locked" errors when running software instance tests.

See merge request !206

buildout profiles and .installed.cfg, shared parts signatures

  Extend getBusinessTemplateList to install the dependencies
  slapos_configurator: slapos_jio_zh_ui_test also goes on keep bt5 list

This change allow us to use slapos node boot/bang under a slaprunner (or any non-root environment).

It should be usefull to not create ad-hoc implementation for those procedures.

/cc @jerome @tomo @Nicolas

See merge request !214

  This allow the user uses slapos node boot inside webrunner or any other non-root environment

  This change allow bang been called on slaprunner or on any unprivileged deployment

This reverts commit 8a3c8aa3 because we
still have complaints for binaries that are linked, directly or not, to
libgfortan (e.g. openblas). Adding zlib to the rpath of these binaries
would be annoying.

See nexedi/slapos@6db91afc

See merge request !213

See merge request !192

See merge request !210

When we recurse in instance to find nested slapos that might be using
parts from ourselves, we check all files named slapos.cfg but we may
encounter some slapos.cfg that are not actual slapos config files, for
example in testnodes we have a working copy of slapos repository which
contains a stack/slapos.cfg which is completly different.

This was breaking prune with an error like this:

    2020-04-29 20:07:28 slapos[2097] DEBUG Reading config at /srv/slapgrid/slappart9/srv/testnode/czp/slapos-repository/stack/slapos.cfg
    2020-04-29 20:07:28 slapos[2097] ERROR No section: 'slapos'

Translation of additional forms (already merged) in Chinese.

Please @lu.xu review the translation (and merge if it is appropriated)

See merge request !209

New fields where added

  Replace String Field by a selection with the list of Countries available on ERP5,
  so it is consitent with general ERP5 Implementation

See merge request !208

the rpath we set in LDFLAGS is not honored here, but we can ignore this
as rpath is needed on executables and not important on shared objects.

libgfortran.so is a shared object that happens to be executable, so it
appears in our ldd check, but we are not executing it directly so it
should be OK.

prune was not recursive when checking dependencies, for example when we
have for example a shared part for openssl that is used only by a shared
part for curl that is not used, we had to run prune twice, the first
iteration would remove curl and only the second iteration would see that
openssl is not used.

This prune in a loop until nothing is pruned by the last iteration. To
support dry-run, we added a ignored_shared_parts parameter to ignore the
parts that are supposed to be deleted.

See merge request !205

This was in plantuml test, but can be used in other cases where we want
to snapshot test screenshots or images produced by softwares.

See merge request !203

prune was not recursive when checking dependencies, for example when we
have for example a shared part for openssl that is used only by a shared
part for curl that is not used, we had to run prune twice, the first
iteration would remove curl and only the second iteration would see that
openssl is not used.

This prune in a loop until nothing is pruned by the last iteration. To
support dry-run, we added a ignored_shared_parts parameter to ignore the
parts that are supposed to be deleted.

eval is not needed here

This snapshot in its current implementation is too slow to run every
minute, especially because the pidfile used to prevent concurent
execution of du is currently never set in config.