Merge pull request #621 from perroned/hangup-webrtc-call2

...tton/conference/service/messaging/MessagingConstants.java

...button/conference/service/voice/VoiceMessageListener.java

...main/scala/org/bigbluebutton/core/BigBlueButtonInGW.scala

...button-client/resources/prod/lib/bbb_webrtc_bridge_sip.js

bigbluebutton-html5/app/client/globals.coffee

bigbluebutton-html5/app/client/lib/bbb_api_bridge.coffee

bigbluebutton-html5/app/client/main.coffee

bigbluebutton-html5/app/client/main.html

bigbluebutton-html5/app/client/stylesheets/chat.less

bigbluebutton-html5/app/client/stylesheets/style.less

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

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

bigbluebutton-html5/app/config.coffee

bigbluebutton-html5/app/lib/router.coffee

...uebutton-html5/app/server/collection_methods/users.coffee

bigbluebutton-html5/app/server/redispubsub.coffee

bigbluebutton-html5/app/server/user_permissions.coffee