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* remove `UriPathHandlerMapping` as superseded by `IntegrationRequestMappingHandlerMapping`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