correct build warnings in akka-apps

...n/scala/org/bigbluebutton/core/OutMessageGatewayImp.scala

...n/scala/org/bigbluebutton/core/apps/PermissionCheck.scala

...scala/org/bigbluebutton/core/apps/PresentationModel.scala

.../scala/org/bigbluebutton/core/apps/SharedNotesModel.scala

...ton/core/apps/chat/ClearPublicChatHistoryPubMsgHdlr.scala

...ebutton/core/apps/chat/SendPrivateMessagePubMsgHdlr.scala

...bluebutton/core/apps/presentation/PresentationApp2x.scala

...pps/presentation/SyncGetPresentationInfoRespMsgHdlr.scala

...ore/apps/screenshare/GetScreenshareStatusReqMsgHdlr.scala

...igbluebutton/core/apps/screenshare/ScreenshareApp2x.scala

.../ScreenshareRtmpBroadcastStartedVoiceConfEvtMsgHdlr.scala

.../ScreenshareRtmpBroadcastStoppedVoiceConfEvtMsgHdlr.scala

...s/screenshare/ScreenshareStoppedVoiceConfEvtMsgHdlr.scala

...igbluebutton/core/apps/sharednotes/SharedNotesApp2x.scala

...tton/core/apps/users/EjectUserFromMeetingCmdMsgHdlr.scala

...n/core/apps/users/MeetingActivityResponseCmdMsgHdlr.scala

...rg/bigbluebutton/core/apps/users/MuteUserCmdMsgHdlr.scala

.../apps/users/UserJoinMeetingAfterReconnectReqMsgHdlr.scala

...g/bigbluebutton/core/apps/users/UserLeaveReqMsgHdlr.scala

...in/scala/org/bigbluebutton/core/apps/users/UsersApp.scala