tap_ipv6 option let you chose if you want IPv6 on the taps or not. Some
customers may decide to have only IPv4 inside their VMs.

We put only 1 address on the tap itself (e.g.
2001:67c:1254:e:89:69b0:ffff:ffff/128 instead of
2001:67c:1254:e:89:69b0:ffff:ffff/96) otherwise, when we assign the
address 2001:67c:1254:e:89:69b0::/96 inside the VM, the address has
"dadfailed" status (dad = "Duplicate Address Detection"). The problem
appears only with address "0" (ending in ::) but not with others
addresses. We had 2 solutions:
 * put only one address on the tap (the solution we choose)
 * forbid address "0" inside the VM

The chosen solution has the advantage that the host machine won't
answer the ping on behalf of the VM since the tap has only 1 address
(its own).

/cc @alain.takoudjou

/reviewed-on !86

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

The bridge was never used anymore. For KVM software release, we are using tap with their own routes (packets are routes directly through the tap device).

Hiding such environment variable prevent easy access to the user
owning the software or the user owning the instance.

Some instances needs to have the actual username of the instance in their
config files and some softwares needs access to the username of user
building the software. This is - in theory - easy to do in zc.buildout
thanks to https://collective.github.io/collective.recipe.grp/ , but the
way slapos run buildout with some environment variables hidden made it
not possible.

Fixes [#20180402-716ACB](https://nexedi.erp5.net/bug_module/20180402-716ACB/)

/reviewed-on !41

We only had a global "pidfile" configuration, but it's more conveniant
to be able to configure different pidfile for each command (software,
instance, report)

The supported config file would look like:

```
[slapos]
pidfile_software = /path/to/pid
pidfile_instance = /path/to/pid
pidfile_report = /path/to/pid

```



/reviewed-on !29

  This version include initial plugin system and cgroups integration.

  We also included a significant change for provide the partitions network informations, which now
  don't require to come from slapos master anymore, so it is possible to make local extensions.