Remove double tagit initialisation

tagit was initialized from both the AdminTagWidget, and from the `done`
method in the image uploader. Initializing it twice led to strange
errors and ultimately the tags not being saved on the image model.

As the tag widget now contains its own initialisation <script>, tag
inputs do not need to be specially handled by AJAX code any more, so
this can simply be removed.

Fixes #2142

CHANGELOG.txt

@@ -15,6 +15,7 @@ Changelog
  * Fix: `ChooserBlock` now correctly handles models with primary keys other than `id` (alexpilot11)
  * Fix: Fixed typo in Wistia oEmbed pattern (Josh Hurd)
  * Fix: Added more accurate help text for the Administrator flag on user accounts (Matt Fozard)
+ * Fix: Tags added on the multiple image uploader are now saved correctly
 
 1.3.1 (05.01.2016)
 ~~~~~~~~~~~~~~~~~~

docs/releases/1.4.rst

@@ -34,6 +34,7 @@ Bug fixes
  * ``ChooserBlock`` now correctly handles models with primary keys other than ``id`` (alexpilot11)
  * Fixed typo in Wistia oEmbed pattern (Josh Hurd)
  * Added more accurate help text for the Administrator flag on user accounts (Matt Fozard)
+ * Tags added on the multiple image uploader are now saved correctly
 
 
 Upgrade considerations

wagtail/wagtailimages/static_src/wagtailimages/js/add-multiple.js

@@ -105,9 +105,6 @@ $(function() {
                 itemElement.addClass('upload-success')
 
                 $('.right', itemElement).append(response.form);
-
-                // run tagit enhancement
-                $('.tag_field input', itemElement).tagit(window.tagit_opts);
             } else {
                 itemElement.addClass('upload-failure');
                 $('.right .error_messages', itemElement).append(response.error_message);