Added unit tests for two workflow examples
- added the ConcatenateExampleTest and RandomLinesExampleTest classes.
- made the example classes return whether the workflow ran successfully.
- added two Galaxy workflow definition files: rna-seq-dge.ga and RemoveTopAndLeft.ga (and updated the GalaxyWorkflowEngineMetadataTest.testGetWorkflows method).
- worked on the RemoveTopAndLeftExample class, but this is still failing.