Add select2 3.5.2
Reference select2 styles in asset pipeline
select2 and bootstrap should play nicely together
BulkTagger prettifies tags

* Required now Select2 submits ugly compact tag lists (e.g. 'this,that,other').
Make mapping tag feature read consistently
Parse tags into Select2 multi-value
Eschew ids in favour of classes for the tag list hooks
Ensure "," breaks to create a new tag
Set up autocompleteWith for tags on client side
Add tagging details to style guide

* Describe and provide examples for Select2 usage
* Include non-js, pre-filled and empty examples with labels
Use smart quotes in tag_list_field
Autocomplete with most popular tags
Override select2 styles for in-input tags
Declare select2-bootstrap explicitly now we no longer have require_tree
Remove some important!s with specificity
Make comments not lie about reasons

* Also remove some unnecessary rules
Style select2 tags/input to match existing styles

* Upgrade select2-bootstrap css to the latest Bootstrap 3 version from
https://github.com/fk/select2-bootstrap-css
* Include the select2 styles after bootstrap, but before our own styles
* Separate out key tag styles into silent SASS classes for extension by
select2
Remove visited tag styles

Purple visited tag styles aren’t needed yet, and cause breakages with
select2 tags
Align tag text input with existing tag choices
Fix failure to act when all common tags removed