INT-2312: HTTP RequestMapping support

The general idea 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* remove `UriPathHandlerMapping` as superseded by `IntegrationRequestMappingHandlerMapping`

JIRA: https://jira.springsource.org/browse/INT-2312, https://jira.springsource.org/browse/INT-2619
INT-2528: Remove deprecations in HTTP module

JIRA: https://jira.springsource.org/browse/INT-2528
INT-2312: Doc for `<request-mapping>`

* Add description to Reference Manual about `<request-mapping>`
* Additional doc polishing
* Add additional test for `<request-mapping>`
* Polishing according PR's comments
INT-2312: 'What's new' and http doc polishing
INT-2312: Add Jackson 2 support for HTTP-inbound
INT-2312: Rebase polishing
INT-2312: Review & email discussion polishing

* Make `RequestMapping` public
* Introduce `HttpContextUtils` and move `HANDLER_MAPPING_BEAN_NAME` to it
* Revert and deprecate public API
* Improve JavaDocs
* Improve Reference Manual
* Rework `IntegrationRequestMappingHandlerMapping` according to email discussion
INT-2312: Polishing after rebase
INT-2312: Docs polishing and tests