This includes the course key/path for a given contentserver request,
 whether or not the asset is locked, cacheable, has been modified, etc.

This should give us some better insight as to what sort of requests
 are coming into the contentserver to figure out whether or use of
 a CDN in front of these assets is as efficient as effective as it
 could be.

This reverts commit 09586d8a.

This includes the course key/path for a given contentserver request,
whether or not the asset is locked, cacheable, has been modified, etc.

This should give us some better insight as to what sort of requests are
coming into the contentserver to figure out whether or use of a CDN in
front of these assets is as efficient as effective as it could be.

This introduces a mechanism to control the time-to-live for an unlocked
course asset, which will allow browsers and intermediate proxies/caches
to cache these course assets, determinstically.

Locked assets, with their nature of requiring authorization, are not
eligible for caching.

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

Have not been able to work out why.

instead of a 500 error. Add 404 test.

TE-489

First step in moving assets out of the contentstore (optionally).
https://openedx.atlassian.net/browse/PLAT-77

PLAT-104

PLAT-104

This commit makes the following changes:
1. If there are syntactic errors in the Range header, it is ignored and
the full content is returned. This conforms to the spec.
2. In case of multiple ranges in the header, the full content is returned.
This behavior differs from the spec which says that a multipart response
should be returned.

PLAT-104

Currently, users can only download ContentStore files from first byte to
last byte.

With this change, when a request to the ContentStore includes the HTTP
"Range" parameter, it is parsed and StaticContentStream will stream the
requested bytes.

This change makes possible to stream video files (.mp4 especially) from
the ContentStore. Users can now seek a specific time in the video
without loading all the file.

This is useful for courses with a limited number of students that
doesn't require a dedicated video server.

Conflicts:
	cms/djangoapps/contentstore/views/tests/test_container_page.py
	common/djangoapps/external_auth/tests/test_shib.py
	common/djangoapps/student/tests/test_login.py
	common/lib/xmodule/xmodule/modulestore/tests/django_utils.py
	common/lib/xmodule/xmodule/modulestore/tests/factories.py
	common/lib/xmodule/xmodule/modulestore/xml_importer.py
	lms/djangoapps/branding/tests.py
	lms/djangoapps/courseware/tests/test_submitting_problems.py
	lms/djangoapps/courseware/tests/test_video_handlers.py
	lms/djangoapps/instructor_task/tests/test_base.py
	lms/djangoapps/instructor_task/tests/test_integration.py

LMS-2876

Refactor get_parent_locations STUD-1663

LMS-2801

[LMS-2757]

This commit updates common/djangoapps.

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]

This reverts commit a517dc20.

This reverts commit ec01253e, reversing
changes made to ae8c9710.

as a first step to separating db connection from modeling
and to support location mapper and contentstore using same db config as modulestore

   And include Don's fix for partial course_id lookup.

        Includes static server tests.