Determine group based on a remote

[FilipMalczak]

Now that this plugin can configure more than version itself (since b643362), it could be useful to try and analyze GIT remote URL and figure out group based on it (in case of standard GIT hosts, like GH).

It should:

• be enabled/disabled via extension
• support default group (in case of clone with remote removed or fork to another hosting)
• take subprojects into consideration