WIP: Delete and edit things

This branch intends to make it so you're able to edit and delete all your submitted information, which I think is important functionality. 

It also fixes a couple of minor bugs (phone numbers were behaving funkily, but I think that was a problem with the fixture-generated data) sort of along the way. 

Current challenges:

- Replacing built-in (horrid) Rails confirmation prompts with pretty, friendly Vex prompts
- You can edit a job application, but it doesn't redirect properly, so it seems as though you didn't, in fact, edit it successfully. 
- Editing an interview and/or a job offer works as expected. It seems like the issue is the json form tag—I'm not sure how to work around this. 

@tofumatt, can I get a little nudge in the right direction on this one?
I added the .posting bit, which makes a functional difference.