Don't log the full response body after successful registration.

fixes codecentric#590 (new client - old server)

Author: joshiste

spring-boot-admin-starter-client/src/main/java/de/codecentric/boot/admin/client/registration/ApplicationRegistrator.java

@@ -70,9 +70,9 @@ public boolean register() {
 
                 if (response.getStatusCode().equals(HttpStatus.CREATED)) {
                     if (registeredId.compareAndSet(null, response.getBody().get("id").toString())) {
-                        LOGGER.info("Application registered itself as {}", response.getBody());
+                        LOGGER.info("Application registered itself as {}", response.getBody().get("id").toString());
                     } else {
-                        LOGGER.debug("Application refreshed itself as {}", response.getBody());
+                        LOGGER.debug("Application refreshed itself as {}", response.getBody().get("id").toString());
                     }
 
                     isRegistrationSuccessful = true;