0.8.11.0

• Update Summernote to 0.8.11
• Fix import behaviour (thanks to Jorge Klemm)
• Fix onBlurCodeview to use Summernote callback
• Remove warning by removing regex at path() (thanks to Ant Somers)
• Add Django 2.0 usage on README (thanks to Ant Somers)
• Make test suite pass on Django master branch (thanks to Claude Paroz)
• Fix widget rendering repeatly (thanks to Andrew Cordery)