XD-282 Dataset support to store POJOs with Avro

(first iteration)

polishing/formatting on merge
XD-282 Adding an avro sink

(similar to the hdfs sink)

- adding parser and integration tests
- enabling the HdfsOutboundChannelAdapterIntegrationTests using filesystem for Hadoop FS

formatting xml for avro sink
Remove serialization warning
XD-871: Show error message for port in use
Remove Servlet API from xd-hdfs
XD-1033: Add a tcp-client source module
XD-1035: Prevent module creation with same name and type
XD-1029 Use Redis Endpoints from SI

Remove temporary endpoints from XD and use the versions that
are now in Spring Integration.
XD-282 overriding CDK dependency for Snappy to version 1.1.0 attempting to solve CI test issues
XD-282 limiting CDK/Avro Snappy version 1.1.0 upgrade to testRuntime
XD-282 adding runtime override for CDK/Avro Snappy version 1.1.0 for spring-xd-hadoop
Rename CompositeModuleRegistry to DelegatingMR
Add support for Spring Boot.

* Create spring-xd-exec project which build executable jar.
* Add Cloudfoundry manifest.
* Add cloud profile
* The'legacy' profile contains old definitions for non-boot use and will
  be removed, along with 
* Create Spring boot application classes. Legacy 'main' classes will also
  be removed later.
Javadoc fixes.
XD-956: Parser refactoring
Minor fixes
Only clean dir if it exists in FileSourceModuleTests

If other initialization fails, we get an IllegalArgumentException
from the AfterClass method.
Fix possible overwriting of XD_TRANSPORT in tests

Attempt to fix problem in CI build where rabbit transport
is being used unexpectedly in stream integration tests which
should be using local transport but are loading rabbit files.
Add better test failure explanation
Update Spring, SI, MQTT Versions

- Spring 4.0.0.RC1
- SI, MQTT 4.0.0.M1