Prefix userName/password with 'form', so that each provider has it's own

prefix on its variables.

@@ -133,8 +133,8 @@ define(function(require) {
             };
             this.attachProviderData = function(data) {
                 _.extend(data, {
-                    userName: this.get('userName'),
-                    password: this.get('password'),
+                    formUserName: this.get('userName'),
+                    formPassword: this.get('password'),
                 });
             };
             bindMethods(this, 'login', 'logout', 'attachProviderData');