Replace LooseVersion
    
    pylint is having a hard time with distutils.version in tox's virtual
    envs. virtualenv uses some tricks to provide a virtual distutils
    package, pylint can't cope with.
    
    https://github.com/PyCQA/pylint/issues/73 suggests to use pkg_resources
    instead. pkg_resources' version parser has some more benefits, e.g. PEP
    440 conformity. But pkg_resources.parse_version() is a heavy weight solution
    with reduced functionality, e.g. no access to major version.
    
    For API_VERSION and plugin version we can use a much simpler and faster
    approach.
    
    https://fedorahosted.org/freeipa/ticket/6468
    
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Martin Basti <mbasti@redhat.com>
    Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>