Refactor the controllers

One of the things that we can notice now that we have both Book and Reader created is that both controllers seem to have a lot of code repetition.

For instance, if we compare the createReader and createBook controllers we can see most of the code is the same.

1. Have a go at writing a helper function createItem which is general enough to work for both controllers.

2. Can you think of how you could write more helper functions so that all CRUD operations are abstracted away in a helper file?

3. When refactoring, your tests are your corner stone. There should be no errors on the tests before you start refactoring and there should be none by the end of it!

4. Refactoring code to make it DRY is something that is part of a software developer workflow. The less code we have the less bugs it'll be likely to have, or the easier they are to fix. It's also a great way of reverse engineering logic and gaining practice in changing code with the support of tests.

5. Have a peak at part of our refactor solution in this commit if you feel like having some inspiration. Try to understand what is happening and why, but then write your own code. You can do this!