SuSE based distributions get the `gid` from `users` not the `gid` from it's name. Fixes #7003.

Full explanation about why is this can be seen here:

  https://github.com/saltstack/salt/issues/7003#issuecomment-23813071
Merge pull request #7047 from s0undt3ch/0.16-merge

[0.16] SuSE based distributions get the `gid` from `users` not the `gid` from it's name