Allow network ip addresses
    
    Currently cloud environments uses heavily prefix /32 (/128) what makes
    IPA validators to fail. IPA should not care if IP address is network or not.
    This commit allows usage of network addresses in:
    * host plugin
    * dns plugin
    * server-installer
    * client-installer
    
    https://fedorahosted.org/freeipa/ticket/5814
    
    Reviewed-By: David Kupka <dkupka@redhat.com>