[bs-17], [bs-146] Add some ApplicationContextInitializers

* One for Cloud Foundry and one for the application context ID
* If app runs in Cloud Foundry vcap.application.* and vcap.services.*
will be populated in the Environment
* The ApplicationContext ID is set to something supposedly unique
(e.g. name:index in a Cloud Foundry app)

[#50968415] [#48153639]

spring-bootstrap-samples/spring-bootstrap-actuator-sample/src/test/java/org/springframework/bootstrap/sample/test/ServiceBootstrapApplicationTests.java

@@ -138,7 +138,7 @@ public class ServiceBootstrapApplicationTests {
 		@SuppressWarnings("unchecked")
 		Map<String, Object> body = (Map<String, Object>) entity.getBody().get(0);
 		assertTrue("Wrong body: " + body,
-				((String) body.get("context")).startsWith("org.springframework"));
+				((String) body.get("context")).startsWith("application"));
 	}
 
 	private RestTemplate getRestTemplate() {