virt-aa-helper: test: check for expected profile content
    
    So far the virt-aa-helper tests only checked the return code and thereby
    catched aborts like issues failing to parse the XML. But there is one
    category of virt-aa-helper issues so far untested - not generating the
    expected rule.
    
    This adds a basic grep based checks after each test to match against the
    rule that is expected to be added by the test.
    
    Acked-by: Jamie Strandboge <jamie@canonical.com>
    Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>