Add a utility method called "get_all_list_data" that will iterate throug...

...h a response object's link headers and returns a list of all the json data.  Added tests and Sphinx documentation blocks.  Update modules in the client package to use relative imports, as it is a best practice.  Import get, put, post, and delete methods in client package __init__.py to make it easier for end user and for methods to call the API.
The ultimate goal of testing is to make sure that the code does what it's supposed to do, not simply to exercise the code that you've written. It's not hard to imagine a scenario where the code is refactored in a way that introduces a bug where a chain of links is not followed properly. Even though it may be redundant for the code as written today, it's always a good idea to test all cases to provide a safety net for future changes.