title: OSCAR_SEARCH_FACETS for filtering product lists
body: <p>I am working on an ecommerce website using django oscar. 
  Products are listed and I have to apply filters (e.g. year, price, etc.). Can we use oscar facet for this filtering functionality? </p>
  
  <p>I have tried adding following as per <a href="http://django-oscar.readthedocs.org/en/latest/ref/settings.html#oscar-search-facets" rel="noreferrer">oscar documentation</a>, but don't know how to make it work and render on my front end.</p>
  
  <pre><code>OSCAR_SEARCH_FACETS = {
  'fields': OrderedDict([
      ('product_class', {'name': _('Type'), 'field': 'product_class'}),
      ('rating', {'name': _('Rating'), 'field': 'rating'}),
  ]),
  'queries': OrderedDict([
      ('price_range',
       {
           'name': _('Price range'),
           'field': 'price',
           'queries': [
               # This is a list of (name, query) tuples where the name will
               # be displayed on the front-end.
               (_('0 to 20'), u'[0 TO 20]'),
               (_('20 to 40'), u'[20 TO 40]'),
               (_('40 to 60'), u'[40 TO 60]'),
               (_('60+'), u'[60 TO *]'),
           ]
       }),
  ])
  }
  </code></pre>
  
  <p>Is it even possible to use this for filtering of products, or is there some other way?</p>