hide joinAudio with mic icon if permissions prohibit mic

bigbluebutton-html5/app/client/globals.coffee

bigbluebutton-html5/app/client/views/chat/chat_bar.coffee

bigbluebutton-html5/app/client/views/modals/modals.html

bigbluebutton-html5/app/client/views/users/user_item.coffee

bigbluebutton-html5/app/server/redispubsub.coffee