straighetend the configs:
no more custom source packages
using xvfb for proview compilation (easier)
fix bug with pwr pre-build process killing itself

Go1.15 is incremental improvement over Go1.14 with better compiler and runtime:

https://blog.golang.org/go1.15
https://golang.org/doc/go1.15

Don't drop support for Go1.13 yet, as that (no longer supported) Go
release is still being used by replication-manager and restic
components.

Remain default at Go1.14 yet.

Switch helloworld to Go1.15 and test this patch on that
software-release.

Going Go1.14.10 -> Go1.14.12 brings in runtime and security fixes:

https://golang.org/doc/devel/release.html#go1.14

Tested on helloworld SR.

See merge request nexedi/slapos!860

When invoking tests with setup.py test, missing eggs are installed before
running tests, using their latest available version, but we want to always
install eggs using buildout and using pinned versions.

The section template-slapuser-script creates the "bin/slapos" wrapper
which is needed inside runner-import.sh script.

Otherwise it's almost impossible to check for which node statistics are shown.

Fixes 8d5910dc

Limit stats to frontend entries only, as they are the most important for the
frontend operator, and also having thousands of entries makes the stats page
unusable.

fixes 8d5910dc

Despite the introspection has replaced old style Caddy-based log-access, some
bits were not removed, so remove then now.

fixes 0c830c4c

It was done in frontend partition, but missed in kedifa.

fixes 3469e864

This reverts commit 5d46a499.

Changes to "fix argument parsing" (to allow passing argument containing space)
had a regression that backslash characters are escaped.

Let's go back to slapos.toolbox 0.112 for now.

When updating existing instance, running slapos node instance failed with:

    ln: failed to create symbolic link '/srv/slapgrid/slappart9/srv/frontend-static/logo.png': File exists

This fixes by doing nothing if logo.png already exists

In nexedi/slapos@74d18b9d I switched ERP5 to use caucase certificate, but caucase is not yet usable for this and this caused issues with upgrading existing instances.

We'll maybe try caucase again here, in that case 620c9332 can be reverted if we want to reuse some parts of what was made.

See merge request nexedi/slapos!857

Revert "software/erp5: use a caucase managed certificate for balancer"

This reverts commit 74d18b9d and also follow
up fixup ( 555b26a2 ).

We are not ready to use caucase here, there are still too many problems with
caucase (keys are lost at each SR update etc) and design might still evolve,
so let's go back to self signed certificate for now.

Also remove the promise and the updater, since they are also not working and
causing problems on instances that have been updated (and where the key no
longer match the certificate)

fix balancer CSR generation:

Caucase rerequest uses a CSR *template* and use it to generate
a new CSR with a new key, so we should not use the actual key to
generate this CSR, because it is caucase rerequest job to generate
the key.
Also, we should be careful not to generate a new CSR every time this
command run, otherwise a new key will be generated and a new CSR will
be sent to caucase, but caucase will not sign it automatically (since
we configure it to sign only one certificate).

This means that the case of IP address changes is currently not
supported automatically. To support it we would need to:
  - force generation of a new CSR template
  - force caucase rerequester to request a new certificate (by removing
  existing certificate)
  - force caucased to sign the new certificate

This commit also fix indentation and remove simplefile macro that is no longer used

See merge request nexedi/slapos!837