Work in Progress: Extract users into service

If you want to test this locally, here's what you need to do:

- Pull this branch
- Clone the [semantic_users](https://github.com/travisvalentine/semantic_users) gem
- Bundle `wrap-semantic-ui`
- Clone and start the [semantic-user-service](https://github.com/travisvalentine/semantic-user-service) with `rails s -p 3001`