Drop TestGithub from TestConfig integration tests

These tests apparently caused the GH API to throw a "Maximum number of login attempts exceeded" exception

See http://hudson.openmicroscopy.org.uk/job/SCC-self-merge/169/ to http://hudson.openmicroscopy.org.uk/job/SCC-self-merge/174/.
With this PR merged in, no more Maximum number of login attempts exceeded should be thrown when running the test suite.