BK-1195: Implement chapter history tab
Merge branch '2.0' of github.com:sourcefabric/Booktype into BK-1195

Conflicts:
	lib/booktype/apps/edit/channel.py
	lib/booktype/apps/edit/static/edit/js/booktype/edit.js
	lib/booktype/apps/edit/templates/edit/book_edit.html
BK-1322 Create default roles for Booktype project
Merge branch 'BK-1322' into 2.0
BK-1318 Implement different error message for cover upload
Merge branch 'BK-1318' into 2.0