Fix for ValidationEngine &hiding errors on change.

Copying class attribute to container causes and issue with the JQuery
ValidationEngine. In order to prevent double validation checking, a
simple replace call to copy all but the actual validation[] class.

Also, added a blurOnChange default setting, to allow people to trigger
and blur() event in case of using JQuery ValidationEngine  in order to
immediately hide the validation error message when selecting an option.

select2.js

@@ -568,7 +568,7 @@
             this.body = thunk(function() { return opts.element.closest("body"); });
 
             if (opts.element.attr("class") !== undefined) {
-                this.container.addClass(opts.element.attr("class"));
+                this.container.addClass(opts.element.attr("class").replace(/validate\[[\S ]+] ?/, ''));
             }
 
             this.container.css(evaluate(opts.containerCss));
@@ -833,6 +833,11 @@
             // some validation frameworks ignore the change event and listen instead to keyup, click for selects
             // so here we trigger the click event manually
             this.opts.element.click();
+
+            // ValidationEngine ignorea the change event and listens instead to blur
+            // so here we trigger the blur event manually if so desired
+            if (this.opts.blurOnChange)
+                this.opts.element.blur();
         },
 
 
@@ -2366,7 +2371,8 @@
                 return markup.replace(/&/g, "&");
             }
             return markup;
-        }
+        },
+        blurOnChange: false
     };
 
     // exports