vcsbase: refactor status output signal in VCSBaseClient

There is now a clear distinction between the basic status command
and the status command used to emit parsed output

Change-Id: Ie398a866ffcd8f4cc33b864ddbe23ce9d2e97437
Merge-request: 358
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>
Reviewed-on: http://codereview.qt.nokia.com/3337