Allow multiple locations for posted jobs [MS-956]

When creating a job, you are allowed to choose what sites (if any) a job will be posted to, including to the entire network. If you're purchasing a job instead, the posted sites is defaulted to all sites associated with the package and is read-only.

When adding multiple locations, I decided to turn the "remove" button into a remove toggle. This means you don't have to re-enter the info if you didn't mean to actually click delete. Locations will not be saved unless you click "Add" after entering the required info.
![2014-08-12-095907_315x608_scrot](https://cloud.githubusercontent.com/assets/3379265/3891326/eaef2610-2228-11e4-8dbc-b68413afee84.png)

There's a lot of JS that could use a new set of eyes. I tried to comment it well, but I'm sure it could use more.

All tests pass.