Set current directory to application bundle on startup.

Set the current directory to application bundle on startup. This allows
Qt examples etc. that load resources from the deployment path to work
correctly without modification.

Change-Id: I5846de135c39d2158ee6c1ae21493739c3532239
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>
Remove XFAIL from tst_qgraphicswidget::initialShow2().

The test now passes on Ubuntu, Lucid, too.

Task-number: QTBUG-20778
Change-Id: Id7ddc4b34d03f8fb9af977c0f40615d544934f13
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>