Nicer logging for SecurityManager startup

Happy to open a jira ticket if you'd like to track one there.

Author: Andrew Ash <andrew@andrewash.com>

Closes #678 from ash211/SecurityManagerLogging and squashes the following commits:

2aa0b7a [Andrew Ash] Nicer logging for SecurityManager startup

core/src/main/scala/org/apache/spark/SecurityManager.scala

@@ -146,8 +146,9 @@ private[spark] class SecurityManager(sparkConf: SparkConf) extends Logging {
   setViewAcls(defaultAclUsers, sparkConf.get("spark.ui.view.acls", ""))
 
   private val secretKey = generateSecretKey()
-  logInfo("SecurityManager, is authentication enabled: " + authOn +
-    " are ui acls enabled: " + uiAclsOn + " users with view permissions: " + viewAcls.toString())
+  logInfo("SecurityManager: authentication " + (if (authOn) "enabled" else "disabled") +
+    "; ui acls " + (if (uiAclsOn) "enabled" else "disabled") +
+    "; users with view permissions: " + viewAcls.toString())
 
   // Set our own authenticator to properly negotiate user/password for HTTP connections.
   // This is needed by the HTTP client fetching from the HttpServer. Put here so its