Allow scale size to be changed before broker is started

Fixes #626 and closes #630

Thanks!

Author: Redth

PushSharp.Core/ServiceBroker.cs

@@ -99,11 +99,11 @@ public void ChangeScale (int newScaleSize)
             if (newScaleSize <= 0)
                 throw new ArgumentOutOfRangeException ("newScaleSize", "Must be Greater than Zero");
 
+            ScaleSize = newScaleSize;
+
             if (!running)
                 return;
 
-            ScaleSize = newScaleSize;
-
             lock (lockWorkers) {
 
                 // Scale down