XD-863 Serialization of Spring Batch Context Objects

* Add preliminary support for a series of batch listeners
* Add sample: https://github.com/spring-projects/spring-xd-samples/tree/master/batch-notifications

Jira: https://jira.springsource.org/browse/XD-863

XD-863 Code review changes
Merge branch 'master' of github.com:SpringSource/spring-xd
XD-889 Change default admin port
- Change default admin port from "8080" to "9393"
- Update the UI with the default port
- Fixed the tests that use the default port
- Changed the admin server port to use a very cool port
   number which is XDXD on telephone keypad [idea from: Mark Fisher]
XD-902: Properly close redis connection factory in tests
XD-900 Phase I

PropertyAccessors are now inheritable.

PropertyAccessors provided to the IntegrationEvaluationContextFactoryBean
are now named, to enable normal bean inheritance/override semantics.

This commit changes spel-context.xml to configure a Map instead of a List
of accessors.

Phase II will elevate the factory bean to the parent (module common)
context.
XD-899 container startup without admin

- Use lazyConnectionDataSourceProxy as dataSource for batch
- Added custom JobRepositoryFactoryBean to use this dataSource
Fix some generics warnings, add javadoc
XD-847 Revise the available hadoopDistro options

Available options now are hadoop12 (default), cdh4, hdp13, phd1, hadoop20