[REFACTOR] renamed de.fu_berlin.inf.dpp.ui.widgets.chatControl package

Changed the name to de.fu_berlin.inf.dpp.ui.widgets.chat which also do
not violates package naming convention.

Moved the ChatRoomsComposite from widgets.session to widgets.chat

Change-Id: I8fa219f6648428c221b3791722444a115118fbe4
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1165
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>