Move django-specific static files outside of ckeditor build dir

The fact that they were previously in static/ckeditor/ckeditor
means there is an extra step involved when copying the built
"release" folder from ckeditor-dev/dev/builder/release
Update to CKEditor version 4.3.2
Add source maps for minified javascript
Make custom JSONDecoder work with python 2.6 json module
Bump version to v4.3.2-atl-3.06