filters/cib2pcscmd[alert]: fix missing -f <file> and "value=" prefix
    
    The former is a matter of my sloppiness, the latter of pcs syntax
    being a moving target pass the point it should have been settled:
    https://github.com/ClusterLabs/pcs/commit/c352ce184093fdf0a5b24c3921b2710c85c6ca38
    
    Also the unit test is adjusted.
    
    Resolves: <https://bugzilla.redhat.com/1381522>
    Reported-by: Miroslav Lisik <mlisik@redhat.com>
    Signed-off-by: Jan Pokorný <jpokorny@redhat.com>