OR-640 Add a right bar to the communities activity stream page

* Set to 0px some padding in order to align components.
* Adjust Bootstrap column between the activity stream and the members
widget.
* In members widget :
	* Display 4 members per row.
	* Increase from 15 to 16 the number of members displayed.
Merge pull request #463 in OR/rse from ~RPIGNOLET/rse:OR-640 to master

* commit '4a11fcfa239ae94a94b441456011f3ca5c45ddc2':
  OR-640 Add a right bar to the communities activity stream page