Also, I replaced a number of tearDown methods with addCleanup instead.
And also remove some unneeded patch.stopall() calls.

Now importing settings module from 'django.conf' instead of 'cms.envs.common'.

This reverts commit b8184d18.

[second attempt which addresses bug building Studio]

This reverts commit 1d6fceda.

Respond to review comments:

- Rename build and config files for consistency between lms/studio.
- Fix merge conflicts with lms require config.
- Devstack uses optimized pipeline to skip require JS optimizer step
- Add tests for render_require_js_path_overrides

TNL-652

PLAT-280

PLAT-221

[PLAT-217]

STUD-1658

This commit adds all of cms.

These keys are now objects with a limited interface, and the particular
internal representation is managed by the data storage layer (the
modulestore).

For the LMS, there should be no outward-facing changes to the system.
The keys are, for now, a change to internal representation only. For
Studio, the new serialized form of the keys is used in urls, to allow
for further migration in the future.

Co-Author: Andy Armstrong <andya@edx.org>
Co-Author: Christina Roberts <christina@edx.org>
Co-Author: David Baumgold <db@edx.org>
Co-Author: Diana Huang <dkh@edx.org>
Co-Author: Don Mitchell <dmitchell@edx.org>
Co-Author: Julia Hansbrough <julia@edx.org>
Co-Author: Nimisha Asthagiri <nasthagiri@edx.org>
Co-Author: Sarina Canelake <sarina@edx.org>

[LMS-2370]

Make XBlock client-side runtimes proper classes, so that handlerUrl can
be defined in a per-runtime way, and we can have multiple runtimes on a
single page.

[LMS-1630][LMS-1421][LMS-1517]

[LMS-1614]