Update rendez-vous css files to adapt it to changes introduces in WordPress 4.0

git-svn-id: https://plugins.svn.wordpress.org/rendez-vous/trunk@1008104 b8457f37-d9ea-0310-8a92-e5e31aec5664
Update rendez-vous editor to enable the BuddyPress groups support

git-svn-id: https://plugins.svn.wordpress.org/rendez-vous/trunk@1008117 b8457f37-d9ea-0310-8a92-e5e31aec5664
Update the php files in the includes dir and add the groups one

git-svn-id: https://plugins.svn.wordpress.org/rendez-vous/trunk@1008118 b8457f37-d9ea-0310-8a92-e5e31aec5664