'Decorate the plugin with paths and urls needed to serve static content.
Plugin bunches are decorated with:
* serves_static : whether this plugin will serve static content
If the plugin path contains a \'static\' sub-dir, the following are added:
* static_path   : the filesystem path to the static content
* static_url    : the url to use when serving static content
:type   plugin: ``util.bunch.Bunch``
:param  plugin: the plugin to decorate
:rtype:         ``util.bunch.Bunch``
:returns:       the loaded plugin object'

def _set_up_static_plugin(self, plugin):

    plugin['serves_static'] = False
    static_path = os.path.join(plugin.path, 'static')
    if (self.serves_static and os.path.isdir(static_path)):
        plugin.serves_static = True
        plugin['static_path'] = static_path
        plugin['static_url'] = '/'.join([plugin.base_url, 'static'])
    return plugin
