DrupalHub Group Feature, Release 1.0

This is a rewrite from scratch of branch 9. The reason for rewrite is replacing bootstrap_carousel which was buggy with views_bootstrap which is not.
The branch is functional and passes build with no errors or warnings.
The feature provides:
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* A group type, presented with a panel variant for group node.
* 3 new content types that are presented on the group's page: Project, News, Group banner.
* Includes rewrites to drupalhub_blog, drupalhub_question and drupalhub_video to make them group content. 
* Example of group page is below.
![ps](https://cloud.githubusercontent.com/assets/5853528/2544041/604ecffa-b5fa-11e3-8591-645f1361d650.png)