Changing version number to 2.2-beta

dist/preview release - beta/babylon.2.2.max.js

@@ -5683,7 +5683,7 @@ var BABYLON;
         });
         Object.defineProperty(Engine, "Version", {
             get: function () {
-                return "2.2.0-alpha";
+                return "2.2.0-beta";
             },
             enumerable: true,
             configurable: true

src/babylon.engine.js

@@ -617,7 +617,7 @@ var BABYLON;
         });
         Object.defineProperty(Engine, "Version", {
             get: function () {
-                return "2.2.0-alpha";
+                return "2.2.0-beta";
             },
             enumerable: true,
             configurable: true

src/babylon.engine.ts

@@ -481,7 +481,7 @@
         }
 
         public static get Version(): string {
-            return "2.2.0-alpha";
+            return "2.2.0-beta";
         }
 
         // Updatable statics so stick with vars here