fix demo project action menu tail position (#1723)
fix demo project action menu tail position (#1723)

close #1722 
TeletronicsDotAe/JSQMessagesViewController,adozenlines/JSQMessagesViewController,Lucashuang0802/JSQMessagesViewController,TeletronicsDotAe/JSQMessagesViewController,Lucashuang0802/JSQMessagesViewController,adozenlines/JSQMessagesViewController,perpetio/JSQMessagesViewController,derekjcarter/JSQMessagesViewController,sebastianludwig/JSQMessagesViewController,preeo/JSQMessagesViewController,perpetio/JSQMessagesViewController,derekjcarter/JSQMessagesViewController,derekjcarter/JSQMessagesViewController,sebastianludwig/JSQMessagesViewController,sebastianludwig/JSQMessagesViewController,TeletronicsDotAe/JSQMessagesViewController,preeo/JSQMessagesViewController,jessesquires/JSQMessagesViewController,perpetio/JSQMessagesViewController,Lucashuang0802/JSQMessagesViewController,preeo/JSQMessagesViewController,jessesquires/JSQMessagesViewController,adozenlines/JSQMessagesViewController