Convert edit_subsection, edit_unit, and publishing to RESTful URLs.

CHANGELOG.rst

cms/djangoapps/contentstore/tests/test_contentstore.py

cms/djangoapps/contentstore/tests/test_import_export.py

cms/djangoapps/contentstore/tests/test_item.py

cms/djangoapps/contentstore/tests/test_transcripts.py

cms/djangoapps/contentstore/views/component.py

cms/djangoapps/contentstore/views/import_export.py

cms/djangoapps/contentstore/views/item.py

cms/static/coffee/src/views/unit.coffee

cms/static/js/base.js

cms/templates/overview.html

cms/templates/unit.html

cms/templates/widgets/units.html

cms/urls.py

common/lib/xmodule/xmodule/modulestore/loc_mapper_store.py

common/lib/xmodule/xmodule/modulestore/mongo/base.py

...xmodule/xmodule/modulestore/tests/test_location_mapper.py