XD-2502 Add embedded Kafka server support

- changed KafkaTestSupport to create and shutdown a standalone Kafka server (and associated ZK instance)
- updated the test to use the embedded broker
XD-2490 - Update to use Reactor 2.0 snapshots
XD-2501 upgrade to Spring Boot 1.2.0.RELEASE, Spring 4.1.3.RELEASE and downgrade Reactor to 1.1.2.RELEASE
XD-2501 upgraded boot-gradle-plugin to 1.2.0.RELEASE
XD-2378 Admin UI logout option

* Add `/security/info` REST endpoint, providing security related meta information
* Add integration test for `/security/info` REST endpoint
* Add logout functionality to the Admin UI
  - Ensure the `/security/info` REST endpoint is executed before AngularJS boots
  - Make security meta information available to AngularJS
  - Provide UI components to log out
  - Show the currently logged in user (if logged in and authentication is enabled)
  - If not logged in, redirect to login page

XD-2378 Code Review Changes

XD-2378 Exclude GroovyTemplateAutoConfiguration

XD-2378 Improve test - add `SecurityControllerIntegrationTestsInitializer`
XD-2509 Fix classpath issues for RabbitMQ MessageBus

- override the ThreadContextClassLoader when creating the RabbitMQ consumer, setting it to the MessageBus classloader, thus allowing the proxies based on SimpleMessageListenerContainer$ContainerDelegate to see the proper class
XD-2475 MessageBus Producer Batching

JIRA: https://jira.spring.io/browse/XD-2475

Rabbit: Use a `BatchingRabbitTemplate` if batching is enabled.
Kafka: Set properties

Tested with:

    xd:>stream create foo --definition "time | log"
    xd:>stream deploy --name foo --properties "module.time.producer.batchingEnabled=true,module.time.producer.batchSize=6"

Observe messages appear in log in batches of 6.

    xd:>stream undeploy foo

Observe partial batch is flushed.

(Also added RabbitMessageBus test).

Bump SI to 4.1.1.RELEASE
XD-2316 Fix batch config REST endpoint

 - If the batch job is not deployed and has no entry in batch job repository,
the detailed job info will not be added for that job. We will only show the job
definition/deployment status from XD ZK repositories.
 - Also, make the `/batch/configurations` endpoint to produce only `application/json`
XD-2427 Use repo.spring.io as NPM repository

* Add `.npmrc`
* Add information to `README.md`

XD-2427 Code Review - Fix spelling in `README.md`