Set network.http.sendRefererHeader to 2 on browser config
    
    IPA web UI isn't functional when browser doesn't send http headers.
    
    This patch adds a functionality which sets Firefox network.http.sendRefererHeader configuration option to value '2' which enables it.
    
    Possible values: http://kb.mozillazine.org/Network.http.sendRefererHeader
    
    https://fedorahosted.org/freeipa/ticket/2778