Extracting user methods to Suave gem

* The [Suave](https://github.com/ATNI/suave) gem encompasses the functionality of the `DapperMethods`
  concern for the `User` model and the `DapperClient` functionality that
  it relies on
* The application controller now checks user access to the application
  through the user itself, which calls the `DapperClient` for
  verification
* Also removed the unused name column from the `Users` table