Move VCS topic next to file name

If no file is open, show it next to session/project name

New format is:
* foo.cpp [master] - session - Qt Creator
* session [master] - Qt Creator

Change-Id: I9945396ffadbffa8fca4b397dda33cfa54131997
Reviewed-by: Petar Perisin <petar.perisin@gmail.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>