Django-ckeditor-link

- python3 fix for templatetag (returning b'' instaead of plain string'
(http://makble.com/python-why-lxml-etree-tostring-method-returns-bytes)

- testing for foreign keys that do no more exist, more robustness

- license changed to GPLv2, due to ckeditors link plugin
- backward incompatible change in link_model contrib package : field "page" of CMSFilerLinkBase
changed to "cms_page", for when used as base for cms plugins, it has possible clashes with the
CMSPlugins "page" attribute. ckeditor_link's templatetag will provide fallback logic for some
time.
- CKEDITOR_LINK_ATTR_MODIFIERS setting / concept: support multi widgets easily in link model
forms. see README for more info.

- provide ckeditor_link.link_model, with default abstract link models, a basic version,
and a django-cms / django-filer enabled version.
- backward incompatible change (only if you use the built in template tag):
get_link_style, get_link_target for getting target and style of a link.
- better selenium testing with firefox instead of phantomjs should do on travis CI now!
- dropping django 1.7 support

- support django 1.11
- readme enhanced, for pypi submit a short version only
- new project urls entered
- selenium testing still a mess, still doesnt work on travis CI

- fallback: legacy href values can be migrated into a specified field/attribute