[facet js] minor refactoring and cleanups
* extract facetCheckBoxSelect and facetCheckBoxUnselect
* use $ as prefix for jQuery variable (facet -> $facet)
* other minor rephrasing
# -*- coding: utf-8 -*-
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s specific hooks and operations"""