Remove NSSConnection from Dogtag
    
    Replaced NSSConnection with Python's httplib.HTTPSConnection.
    This class is OpenSSL-based.
    
    A client certificate with a private key is required to authenticate
    against the certificate server. We facilitate the RA_AGENT_PEM which
    already exists.
    
    https://fedorahosted.org/freeipa/ticket/5695
    
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>