Provide support for default priority and default issue type when creating JIRA tickets.

Also expose an auto-create button for filing JIRA tickets.

One known limitation: you must update the project name to update the default issue type if they are different across different projects.  I tried a bunch of different JS approaches to do it, but figured the easier thing for now is just to require 2 saves.

![image](https://cloud.githubusercontent.com/assets/326857/3207131/b0715f6c-edd5-11e3-82fd-fd2f11d13775.png)

This line should already be pulled from request.POST..