/reviewed-on !71

/reviewed-on nexedi/slapos.core!70

[slapos_crm] fix failing crm skins tests after include error message in generated ticket for hosting subscription

After c931d60c, default options were changed and we didn't want that.

Rewrite the code so that we have a clearer scheme:
 * all options of format are listed as FormatConfig attributes with default values
 * all values present in configuration file (.cfg) erase the previous options
 * all values present in command line erase the previous options

We use the special default argparse.SUPPRESS that removes totally the arg from arg dict so that only PRESENT options erase something

fix after nexedi/slapos.core!62

@rafael currently slapos node boot is broken on all machines with ipv6_interface different from interface_name (e.g. rapid space machines)

/reviewed-on nexedi/slapos.core!68

ComputerModelModule_viewComputerModelList was commited by mistake

Some informations are important to have.

Display collected information on Master

Minimal fixes to restructured text so that it renders properly on [pypi index page](https://pypi.org/project/slapos.core)

/reviewed-on !65

Because most txt were renamed as .rst, it makes sense to include all
.rst recursively

  Same as 1.4.12 but with a minor fix on the egg generation, after a rename of CHANGES.txt into CHANGES.rst

  Missing CHANGES.txt fails to install eggs.

Add ofset +0000 to utc date so after convert to another timezone it still remain valid.

/reviewed-on nexedi/slapos.core!63

Each tap will have a subnetwork with 16 more bits than the interface.
The IPv6 of the tap is the last of the subnetwork.

Note: the example IPv6 address is the address used in documentation (see https://en.wikipedia.org/wiki/IPv6_address#Documentation)