User can add an ebook
Extend loan period
Adds active model serializer. Adds basic book serializer.
Removes integration tests and related code.
Adds rails_api and index action/test for books.
Added show and delete actions on books.

Also added rescue for record not found.
Added update action ok books.
Added create action on books.
Replaces clearance with devise. Adds basic token based authentication.
Uses symbols instead of keys in books_spec

Adds symbolize_keys to JSON.parse .
Uses rails helpers for token based auth

Rails can take care of the part of parsing the user token.
The middleware is no longer needed.
Adds users post action

AMS was not being loaded, so all reponses had to be updated to remove
the root name.
Adds tests for token authentication

Renamed the folder from requests to integration based on how other
people organize api tests.
Adds borrow and return actions

The pr adds the borrow and return book actions. I also added
check_authorization to make sure every controller authorises the call.
Some parts of the code I use, like the BookKeeper need refactor, but
that is not on the scope of this PR.
Removes extra README