Fix deploy

This replaces the existing deploy configs with new ones matched to the chef configs I created. It fixes a lot of issues and allows us to run but a few commands to create the server and deploy to it.

This also allows us to run multiple apps per-server, which could even include a staging and production instance on the same server, though we won't do that for now. ^_^

* Partially addresses #79 by automating a LARGE amount of the deployment process, but I won't tick this one off quite yet as there are still like two manual things that need be done on first run
* Fix #90 (this allows us to easily set up a staging site with a separate capistrano config in `config/deploy/staging.rb`)
* Fix #140 (this runs migrations on every deploy)
* Fix #141 (this runs bundle install on every deploy)

This will remain a WIP until I finish the documentation, share with @sarahsemark the chef configs needed to run the site, and I do a few more deploys so we're satisfied this works. But I did manage multiple successful deploys with _very_ minimal intervention via `ssh` already.

Current blockers:

* [x] Disable apparmor via `chef` for Ubuntu 14
* [x] Create MySQL database/user via `chef` instead of manually
* [x] Copy `config/database.yml` and `.env` files to app server via `chef` instead of manually
* [x] Document small amount of "first-run" commands and regular deploy commands (#79)