Merge branch 'release/0.20' into develop
bump version to 0.21-dev since 0.20 has been released
support for adding new (non-predefined) datastreams when ingesting a new object or saving an existing object
fix new add-hoc datastream support so it is stored per-object instead of per-class
remove warning about not building datastreams at ingest, since it is so common
revise log message for clarity
remove references to deprecated django.conf.urls.defaults
small fix to enable saving updates to existing ad-hoc datastreams
add option to pass in list of content models when inferring object subtype
additional details in changelog
set version to 0.21.0 final
Merge branch 'release/0.21'