Add more testing cases to testing package

The main missing part of the testing package is the ability to test authenticated endpoints by allowing us to test 400 series errors. We should add the a new set of methods with a method signature like the following for GET, PUT, POST, and DELETE:

public static void testX(EndpointTestCase testCase(, Object body), int statusCode)

The body section of the method should only be set if the method accepts a body. We should also add more visible support for null body arguments by adding overloaded calls without the body parameter that assumes a null value.

We can call up to more and more specific calls with more arguments to inherit all functionality of previous levels more easily.