User can sign up

* Add `bcrypt`, `jbuilder`, `oj` gems
* Create user on `POST /v1/users`
* Create `response_json` test helper
* Create binstubs for `spring`
* Create `users` table
* Create `delayed_jobs` table
Line is too long. [83/80]<br>Use the new Ruby 1.9 hash syntax.<br>Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping.