Refactor feeder implementations to better manage memory and performance.
Remove feed queues, replaced by an internal feed queue.
Update testtools implementations to use StreamFeeder instances.
Refactor executor interfaces to provide different types of result handlers.
Add basic documentation to internal execute queue.
Add java worker verticle implementation.
Add java feeder verticle implementation.
Add java executor verticle implementation.
Refactor feeder verticle to use handle* methods for clarity.
Replace static factory methods from DefaultJsonMessage with JsonMessage builder usage.
Refactor JsonMessage to use 'root' messages not 'ancestor'.
Use constants in constructing/replicating JsonMessage instances.