fix error handling when client parts fail to load

bigbluebutton-client/locale/en_US/bbbResources.properties

...ent/src/org/bigbluebutton/core/managers/ConfigManager2.as

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

...c/org/bigbluebutton/main/model/modules/EnterApiService.as

...ent/src/org/bigbluebutton/main/model/users/JoinService.as

...n-client/src/org/bigbluebutton/main/views/LoadingBar.mxml

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

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