Refactor installer code requesting certificates
    
    - Temporary modify certmonger dogtag-ipa-ca-renew helper to request the IPA RA
    agent cert, using the temp cert created during pkispawn. The cert request
    is now processed through certmonger, and the helper arguments are restored
    once the agent cert is obtained.
    
    - Modify the installer code creating HTTP and LDAP certificates to use
    certmonger's IPA helper with temporary parameters (calling dogtag-submit
    instead of ipa-submit)
    
    - Clean-up for the integration tests: sometimes ipa renewal.lock is not
    released during ipa-server-uninstall. Make sure that the file is removed
    to allow future installations.
    
    https://fedorahosted.org/freeipa/ticket/6433
    
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>
    Reviewed-By: Fraser Tweedale <ftweedal@redhat.com>