INT-3165: Deprecate Jackson 1.x Usage

JIRA: https://jira.springsource.org/browse/INT-3165

INT-3165 Polishing

Remove unnecessary SuppressWarnings.
INT-3184: Test HTTP Matrix Variables

JIRA: https://jira.springsource.org/browse/INT-3184

* Change `IntegrationRequestMappingHandlerMapping` to postpone
Handlers detection as late as possible using `ApplicationListener<ContextRefreshedEvent>`