Add support for permitting cross origin requests (CORS)

The Spring MVC 4.2 has introduced @CrossOrigin mapping for the @Controller methods.

Similar to the org.springframework.integration.http.inbound.RequestMapping the org.springframework.integration.http.inbound.CrossOrigin can be introduced as a domain object to be injected to the HttpRequestHandlingEndpointSupport and processed by the IntegrationRequestMappingHandlerMapping overriding the new initCorsConfiguration() method.

From the XML perspective it can be represented as a nested <cross-origin> tag alongside with <request-mapping>