Log INFO message when reloading SSL configuration file changes (elastic/x-pack-elasticsearch#1082)

This commit adds a INFO level log message to indicate that a file was reloaded and the SSL contexts
using the file were also updated.

relates elastic/x-pack-elasticsearch#1063

Original commit: elastic/x-pack-elasticsearch@f53f7019de

plugin/src/main/java/org/elasticsearch/xpack/ssl/SSLConfigurationReloader.java

@@ -114,11 +114,17 @@ public class SSLConfigurationReloader extends AbstractComponent {
 
         @Override
         public void onFileChanged(Path file) {
+            boolean reloaded = false;
             for (SSLConfiguration sslConfiguration : sslConfigurations) {
                 if (sslConfiguration.filesToMonitor(environment).contains(file)) {
                     reloadSSLContext(sslConfiguration);
+                    reloaded = true;
                 }
             }
+
+            if (reloaded) {
+                logger.info("reloaded [{}] and updated ssl contexts using this file", file);
+            }
         }
     }
 }