Include diffs for all errors when testing - don't stop at first.
Gives more details to aid testing (especially for tools with lots of outputs) and lets developer collect all correct test data files at once (when GALAXY_TEST_SAVE is set or using `planemo test` with --job_output_files argument) instead of needing to rerun the tool repeatedly.
Twill interactor for tests is broken - so I am deleting.
It wasn't long for this world with a JavaScript tool form anyway - would be nice to implement a casperjs driven interactor though so the UI could be exercised for tests.