refactor pipes to include all graph-related pipes that were originally in Gremlin. this requires a depedency on Blueprints. Pipes is now a graph dedicated project.
move GremlinStartPipe out of Pipes.
fixed up to support CompareRelation.
updated CHANGELOG with 23 branch features.
CompareRelation work propagated through.
Changed CompareRelation to Predicate.
Changed Predicate.compare() to Predicate.evaluate()
Moved GremlinToStringPipe to Pipes and called it ToStringPipe.
added JavaDoc to toStringPipe.
fixed an NPE bug in ToStringPipe and added TestCase.
Merge remote-tracking branch 'upstream/master'