Fixed the assertions and test code cleanup

I cleaned up the tests file so it will more accurately detect future breakages. Many of the string-comparison assertions were passing even though they weren't correctly checking the strings.

One test in particular, testGraphApiMethodWithOAuthSpecError(), was failing to detect such a bug. I corrected the test which causes a new test failure. The fix is trivial since the problem is a mismatched exception message, but I'll leave it to others to figure out whether the test or the code is incorrect. :)

I also renamed many of the stub classes so they all follow a single convention and cleaned up some formatting to follow the existing standard.