Custom plugin support

[Angelo-Verona]

• Added option to install nexus-repository-apt plugin
• Fixed some types, there and there
• Adjusted version recognition as previous one was confusing as both could be defined at once

[philippkahr]

Hi there,
Thanks for the pull request. I do see an issue here, that you are requiring major.version to be set. This breaks compatibility, due to the lack of setting major.version to the v2 pillar format which is required by the v2 formula. When I first merged v2 and v3, I did not rewrite v2 and only separated them per folder and init.sls. I do not know how many are still using the v2.

Please rework the major.version setting, than I will allow this PR.

[Angelo-Verona]

Thanks for the reply, I need to look at the issue even further. After some more testing seems that functions file.line are behaving kind of buggy in salt itself and tend to remove some lines randomly just for fun, looking for a workaround. There are few tickets already opened on it.
And to version issue...I would probably split these two things. As always, when you are trying to manage something very legacy with something new and different, you need test two things at once...which is not always possible and you tend to break more things than fix or add.
So I would rather fork and freeze V2 and have it always stable as a fanbase to that version will drop over time more and more. Backporting is still an option for one's needs.

[philippkahr]

Currently, V2 is somewhat frozen already, as long as you don't change the init.sls behavior. I do not think that it makes sense to separate it. (this was briefly discussed in another pull request).
Yeah sure take your time, just submit your fix and I will allow this pull request.