[HOTFIX] Fix scala style issue introduced by #2276.

yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/YarnRMClientImpl.scala

@@ -98,7 +98,7 @@ private class YarnRMClientImpl(args: ApplicationMasterArguments) extends YarnRMC
     // Users can then monitor stderr/stdout on that node if required.
     appMasterRequest.setHost(Utils.localHostName())
     appMasterRequest.setRpcPort(0)
-    //remove the scheme from the url if it exists since Hadoop does not expect scheme
+    // remove the scheme from the url if it exists since Hadoop does not expect scheme
     appMasterRequest.setTrackingUrl(new URI(uiAddress).getAuthority())
     resourceManager.registerApplicationMaster(appMasterRequest)
   }