Don't display the speaker comment form if review period is over

I also display a nice message about how much longer the review period is active, if there is one. 
![screen shot 2014-10-06 at 3 07 13 pm](https://cloud.githubusercontent.com/assets/1054089/4534550/0ac66abc-4da7-11e4-8b24-5227788453cc.png)

(Sorry about the messy commit history - I got it mucked up with another pull request. I can't git properly.)