[bug 1086643] [bug 1086650] Redo infrastructure for product picker versi...

...on

This redoes the infrastructure for having the generic form and the
product-picker version of it "live" simultaneously.

* nixed all the extra routing in favor of a waffle flag "feedbackdev"
* extracted product-picker specific unit tests and put them in their own file
* wrote a with_waffle class/function decorator that lets us more easily
  test waffley things
* added WAFFLE_OVERRIDE=True to settings--we always want to be able to
  explicitly set the waffle flag via the url
* added smoke tests for the dev form and product picker page

r?
This router logic is slightly different than the current router logic hence separating it completely rather than mixing the two. It'll make it easier to ditch one and switch to the other in the future.