Remove Facebook support, some bugs fixed and minor code improvements

git-svn-id: https://plugins.svn.wordpress.org/wp-meetup-activity/trunk@1031812 b8457f37-d9ea-0310-8a92-e5e31aec5664
Committing release 0.1.7

git-svn-id: https://plugins.svn.wordpress.org/wp-meetup-activity/trunk@1031814 b8457f37-d9ea-0310-8a92-e5e31aec5664