INT-2433: Get Rid of MessageProcessors wrapping

Previously, provided `MessageProcessor` to create a `MessageHandler`
for endpoint was wrapped to `MethodInvokingMessageProcessor`,
e.g. `GroovyScriptExecutingMessageProcessor`.

Check the type of provided object in the constructor
of `MethodInvoking*` strategies and use it directly if it is `MessageProcessor`

JIRA: https://jira.springsource.org/browse/INT-2433
INT-3139: Add #jsonPath SpEL Function Support

* #jsonPath function is registered automatically if the library is on the classpath
* Add otional dependency on `com.jayway.jsonpath:json-path` artifact
* Add `JsonPathUtils` class as a wrapper around `JsonPath`
* Add `#jsonPath` tests for: `<transformer>`, `<filter>`, `<splitter>`, `<router>`

JIRA: https://jira.springsource.org/browse/INT-3139

INT-3139: Further improvements

* Remove `SpelFunctionRegistrar`
* Introduce `SpelFunctionFactoryBean`

INT-3139: Polishing
INT-3144 Fix JMX Tests Timing Issue

Really only an issue with the queue channel test, but change
all tests to use CountDownLatches instead of relying on Thread.sleep().
INT-2867: Add Script Support to inbound-c-a

* Add `<script>` and `<expression>` to `<int:inbound-channel-adapter>`
* Refactoring for `DefaultInboundChannelAdapterParser`
* Introduce `ScriptExecutingMessageSource` to allow scripts' `MessageProcessor`
implementations work as a source for polling endpoint

JIRA: https://jira.springsource.org/browse/INT-2867

INT-2867: documentation

In addition the tests for Lifecycle attributes

Polishing
DOS->Unix NewLines in Several Core Files
INT-3144 Fix JMX Tests Timing Issue

Really only an issue with the queue channel test, but change
all tests to use CountDownLatches instead of relying on Thread.sleep().
Merge pull request #890 from garyrussell/INT-3144

INT-3144 Fix JMX Tests Timing Issue
INT-3142: A flag to retain default converters when user has customized messageconverters for HttpRequestHandlingController, HttpInboundGateway

* Introduced a new flag in base class of HttpRequHttpRequestHandlingController, HttpInboundGateway - registerDefaultConverters
* Introduced a new attribute "register-default-converters" for inbound-channel-adapter and inbound-gateway to indicate if the default HttpMessageConverter's need to be registered
* Http namespace parser related changes to set the new flag
* Added additional tests to test the flag and the namespace parser related changes

Changes per feedback from Artem - additional javadoc comments, cleaned up tests

Updated: Setting the register-default-converters by default to false now, for backward compatibility reasons
Changed adapter name per feedback from Artem

Changed adapter name per feedback from Artem
Changed attribute name from register-default-converters to merge-with-default-converters