Make mocking cofigurable in Test
Add sumByKey
Merge pull request #663 from twitter/transformTest

Make mocking cofigurable in Test
Merge pull request #664 from twitter/sumByKey

Add sumByKey
mark version 0.9.0rc2, not published
Added System Property to Toggle Loggers in JobTest
- Added system property DISABLE_JOBTEST_LOGGER_APPENDERS to toggle
  Logger Appenders when running JobTests.