Merge pull request #3635 from riadvice/logged-out-confirmation

...src/org/bigbluebutton/main/events/ExitApplicationEvent.as

...ient/src/org/bigbluebutton/main/model/users/Conference.as

...g/bigbluebutton/main/model/users/NetConnectionDelegate.as

...ent/src/org/bigbluebutton/main/views/LoggedOutWindow.mxml

...rc/org/bigbluebutton/main/views/MainApplicationShell.mxml

...-client/src/org/bigbluebutton/main/views/MainToolbar.mxml