Backend unit tests

The new files here are unit tests for the backend handlers and this is roughly how I envision the unit tests for the backend to look.

To run the tests, just navigate into a directory with a test file in it and run `go test`
@ngmiller @zach-taylor probably the biggest thing here for you guys is that all the JSON from the handlers will now be PascalCase (and the backend will expect the same of incoming data as well).  This is because Docker's API uses PascalCase.