solved issue 187, empty friend list warning removed for facebook

187) facebook grant publish_actions messages:
     1) You have granted Gofreerev permission to write on your facebook wall.
     2) Your facebook friend list is empty or Gofreerev is not authorized to see your facebook friend list. No facebook friends and no post from facebook friends are displayed in Gofreerev.
     remove 2) either ignore empty facebook friend list or do not run post login tasks after second "publish_actions" login
added FACEBOOK_FRIEND_LIST ruby constraint and convert oauth 1.0 privs to oauth 2.x format at omniauth login