Refactor get_parent_locations STUD-1663

STUD-1151

Caution! This is backwards incompatible

[LMS-226]
[LMS-2013]

This reverts commit a517dc20.

This reverts commit ec01253e, reversing
changes made to ae8c9710.

change to use regex to do the domain mappings. Also add config to AWS to be able to set from configuration file.

handle cases where HTTP_HOST is none, like in unit tests

add linefeed at end

fix up regex matches

switch to use thread local storage to hold the request itself

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convert over to use open source 3rd party library

convert over to use django-cum

add unit test

remove comment

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add comment to config setting

fix comment

use better regex for localdev

no need to break

no need to wrap an imported function, it's visible to any file that is importing us

add comment

add unit test

clean up test

use a separate env file to set the preview hostname

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

use to instantiate loc_mapper
test loc_mapper injection into split modulestore

Seems like the Edit/QA links in LMS are triggered by a ENABLE_LMS_MIGRATION feature flag. So when running as mongo-backed, set that to False

Make django use_tz

Start linting envs files, add task to only pylint errors, and move pylintrc file to the correct location

Make the lms running alongside the CAS in dev point to the same contentstore, and server up static content

* Note: This doesn't run yet
* add config file for lms on mongo
* Some comment additions and cleanups