BK-1199 Implement book license option in the settings tab
BK-1265 Media upload is broken
BK-1042 Move constants file to new booktype application
Merge branch 'BK1199' into 2.0
Merge branch 'BK827' into 2.0
BK-1269 Script which should validate source code and Booktype integrity
BK-1270 Home page in the Sphinx documentation has error
BK-1267 Django migration is broken with license model changes