Implemented proposal invitation from proposal owner
Fixed some issues of the invite contributors feature
Merge branch 'refs/heads/master' into contribution_invite

Conflicts:
	portlets/proposals-portlet/src/main/resources/friendlyUrlRoutes.xml
	portlets/proposals-portlet/src/main/webapp/css/proposals.css
	services/plansProposalsFacade/plansProposalsFacade-portlet/src/main/resources/service.properties
bugfix in CKEditor
Moved proposal contribution response logic to structs action
Merge branch 'refs/heads/master' into contribution_invite