Notify user about necessary ports in ipa-client-install
    
    Connection error message in ipa-client-install now warns the user
    about the need of opening of all the necessary ports for ipa-client
    enrollment when error that might have been caused by closed ports
    is encountered. Mentions the ports needed after the client
    enrollment as well.
    
    Improves other error messages during installation in various ways.
    
    https://fedorahosted.org/freeipa/ticket/2816