Qbs: Add build file command to Build menu

Task-number: QTCREATORBUG-9353

Change-Id: I221689ae6a37ff22528b5e009615db5bdb192488
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Qt4: Only print the filename in Build file menu entry

Skip the rest of the absolute path.

Change-Id: I487758e872b4747e6432ddbbd3553ae4ad5f86ac
Reviewed-by: Daniel Teske <daniel.teske@digia.com>