Clicking outside of dropdown removes select2-container-active class.

Closes #1661.

select2.js

@@ -1321,7 +1321,7 @@ the specific language governing permissions and limitations under the Apache Lic
             $("#select2-drop-mask").hide();
             this.dropdown.removeAttr("id"); // only the active dropdown has the select2-drop id
             this.dropdown.hide();
-            this.container.removeClass("select2-dropdown-open");
+            this.container.removeClass("select2-dropdown-open").removeClass("select2-container-active");
             this.results.empty();