added write a review stub (bug 847639)

So a couple of notes:

1. Couldn't get ratings to load up in that 'write a review' form. Now I'm not sure it's supposed to be there anyway since there's a ratings button also (which makes me think that should be over there instead?)

2. Persona login relies on listening to .persona attached to a dom element. If I attach this to the 'Write a review' button, then I can't call back to load the overlay. @cvan told me there is some localStorage solution happening on zamboni right now but I think it would be better to attach an optional callback on the login handler. Not sure how you want to do that but I would think it is better than putting stuff into localStorage (and we're not tied to zamboni anymore so this doesn't need to happen I assume).

3. What happens if you go directly to /app/blah/review and load the review page in full and are not logged in? Does it throw up an immediate prompt to sign in with persona but stays blank below or is filled in?

Anyway, let me know, I got as far as this point and would like some input :)