Shorten Smack's executor service names

instead of

"Smack Executor - Foo 42 (2)"

use

"Smack-Foo 42 (2)"

since sometimes the space for the name is limited (e.g. busybox's 'ps
-t').

smack-core/src/main/java/org/jivesoftware/smack/util/SmackExecutorThreadFactory.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2014 Florian Schmaus
+ * Copyright 2014-2015 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,7 +35,7 @@ public final class SmackExecutorThreadFactory implements ThreadFactory {
     @Override
     public Thread newThread(Runnable runnable) {
         Thread thread = new Thread(runnable);
-        thread.setName("Smack Executor - " + name + ' ' + count++ + " (" + connectionCounterValue + ")");
+        thread.setName("Smack-" + name + ' ' + count++ + " (" + connectionCounterValue + ")");
         thread.setDaemon(true);
         return thread;
     }