Add in API to alter canned responses (bug 1063743)

https://bugzilla.mozilla.org/show_bug.cgi?id=1063743

Also moved a couple of existing reviewers serializers to the appropriate file.
Also
![hellyeah](https://cloud.githubusercontent.com/assets/1106/4376165/f126563a-4342-11e4-9add-900e6afcdbaa.jpg)