XD-633 Rabbit Source Improvements

- Make the stream name the default queue.
- Change the parameter to queues (from queue) since a list of queues is supported.
XD-636 Header Leakage in Rabbit Transport

The ARPMH used in the rabbit transport copied the request headers.

This caused the internal transport content-type header to be
restored when there was no original content-type. It also caused
the internal 'originalContentType' header to be restored.
XD-599 Adding placeholders for spring-xd-hadoop sub-projects

The placeholder will fix an issue with the Gradle plug-in or Eclipse not being able to handle
the missing sub-project directories.
Fix tap stream.modulename syntax

XD-592: more tap fixes

Fix compile errors and simplify tests config to use nearly InMemory repos

Added test delete unknown stream