CSPACE-6042: Implement toString() in InvocationError, to return meaningful error messages in log output.
CSPACE-6042: Trivial formatting and comment cleanup in Invocable class.
CSPACE-6042: Avoid returning null as a toString() value from InvocationError.
CSPACE-6065: In services tenant bindings, remove extraneous config block (<service:RefnameDisplayNameField>...</service:RefnameDisplayNameField>) for the Vocabulary service.
Merge pull request #115 from aronr/CSPACE-6065

CSPACE-6065: In services tenant bindings, remove extraneous config block...