INT-2312 Add HTTP RequestMapping support

The general idea is to use Spring-MVC as much as possible.

* Introduce `RequestMapping`, `IntegrationRequestMappingHandlerMapping`
* Introduce XSD nested element `<request-mapping>` for HTTP Inbound Endpoints
* Introduce `inboundCommonAttributes` XSD attributeGroup for HTTP Inbound Endpoints
* Introduce `IntegrationNamespaceUtils#createExpressionDefIfAttributeDefined` & `IntegrationNamespaceUtils#createDirectChannel`
* Remove deprecated `name` attribute
* Remove `UriPathHandlerMapping` as superseded by `IntegrationRequestMappingHandlerMapping`
* Add documentation for `<request-mapping>`
  - Add description to Reference Manual about `<request-mapping>`
* Add documentation to section 'What's new'
* Add additional test for `<request-mapping>`

JIRA: https://jira.springsource.org/browse/INT-2312, https://jira.springsource.org/browse/INT-2619

Additional changes:

* INT-2528 Remove deprecations in HTTP module
  - JIRA: https://jira.springsource.org/browse/INT-2528
* Add Jackson 2 support for HTTP-inbound
* Using Jackson 2 HttpMessageConverter if Jackson 2 is available in classpath
* Make `RequestMapping` public
* Introduce `HttpContextUtils` and move `HANDLER_MAPPING_BEAN_NAME` to it
* Revert and deprecate public API
* Improve JavaDocs
* Improve Reference Manual

Thanks also to Biju Kunjummen for his incorporated commit.