INT-2500: Add annotations global configurations

JIRA: https://jira.springsource.org/browse/INT-2500

* Add `org.springframework.integration.component` package to provide
infrastructure to configure internal Spring Integration components via annotations
* Add `AbstractIntegrationNamespaceHandler#processIntegrationConfiguration` to scan
and register annotated components throughout CLASSPATH from packages by pattern
`org.springframework.integration.[MODULE].component`
* `[MODULE]` placeholder is extracted from `META-INF/spring.integration.properties`
under key `scan.module.[MODULE]`
* Add annotation configuration implementation for core module
* All annotated components are registered only once in the parent context
* Register merged properties from `META-INF/spring.integration.properties` as a bean
under name `IntegrationContextUtils#INTEGRATION_PROPERTIES_BEAN_NAME`
* Add `IntegrationObjectSupport#getIntegrationProperties()`
* There is no test on the matter, but nothing fail
INT-2500: Polishing

* Introduce `IntegrationConfigurationClassPostProcessor` to avoid
double registration of components, if `<context:component-scan/>` is presented
in the application context