title: Expose a Drupal Views filter as an on/off checkbox to enable/disable the filter
body: <p>I have a Drupal view that filters on a taxonomy field. I would like to be able to toggle the filter on/off by exposing a checkbox on the Exposed Filters form.
  To illustrate the problem, say for example the Vocabulary is Fruit, and the Terms are Apples, Pears, Oranges and Lemons. I can select citrus fruit content by creating a filter that says Fruit is one of (Oranges, Lemons). Now I would like to expose the filter to allow me to choose whether or not to apply my citrus fruits filter. How can I add a checkbox to the exposed filters forms that will apply the filter when selected, and ignore the filter when no selected? </p>