#634 Core data tests

There is one last issue with ReaderTests (running the suite, individual tests work), and making them work for running all test suites serially. Starting the PR for review of the test coverage and feedback.

##### Note
There is one test that fails still: one of WPTableImageSource: testResizeImagesSynchronously. It expects the output size to be 200x150, but ends up being 200x133. The resize code lies within the MGImageUtilities pod