Fix ProcessorsTests

- Move `transform-to-lowercase` groovy script into spring-xd-shell
- Update the script option in test case
XD-1378: Add options for router. Add IT test
XD-1378 Router sink test using script

- Also, moved the groovy script location to a package
Misc shell test cleanup

- testDestroyTap() leaves the file source input directory behind, use http source instead.
- use generateStreamName() instead of hard coded names