'Determines whether the given filesystem path contains a plugin.
If the manager ``serves_templates`` and a sub-directory contains another
sub-directory named \'templates\' it\'s considered valid.
If the manager ``serves_static`` and a sub-directory contains another
sub-directory named \'static\' it\'s considered valid.
:type   plugin_path:    string
:param  plugin_path:    relative or absolute filesystem path to the
potential plugin
:rtype:                 bool
:returns:               True if the path contains a plugin'

def is_plugin(self, plugin_path):

    if (not super(PageServingPluginManager, self).is_plugin(plugin_path)):
        return False
    listdir = os.listdir(plugin_path)
    if (('templates' not in listdir) and ('static' not in listdir)):
        return False
    return True
