(SOL-776)(SOL-740)(SOL-532) Added setting flags for COURSE DISCOVERY feature; Exposed course search input as well as the course result page; Added flag for limiting the number of course cards on the homepage;

TNL-1261

This is the first stage of the new Discussion API.

JIRA: MA-604

ECOM-1437

TNL-2054

TNL-1669

TNL-1789

TNL-1796

TNL-1537

Co-Authored-By: Andy Armstrong <andya@edx.org>
Co-Authored-By: cahrens <christina@edx.org>

TNL-1488

TNL-1606

TNL-1545

This reverts commit 228cca4e38ec79f5cbb54098c788ab9556f602e2.

TNL-1740

(SOL-531)(SOL-532)Course Cards update; A link to course discovery page has been added to the OpenEdX homepage

- sharing enabled for custom URLs only if URL actually specified

Final official name is Custom Courses for EdX (CCX), rename all code to remove previous name.

Rename the FEATURE constant used to identify this feature

Rename the middleware for the CCX change

rename the constant used for storing the current poc id on the session.

rename the _PocContext threading local

rename the override provider in all places where it is referenced

`PersonalOnlineCoursesOverrideProvider` -> `CustomCoursesForEdxOverrideProvider`

generally rename symbols from overrides.py to replace `poc` with `ccx` where possible without changing model names or attributes

rename more symbols from poc to ccx
rename util functions from app utils module

general symbol renaming poc -> ccx in views.py and related url changes

Rename the coach role wherever it is used.

reword poc_coach to ccx_coach

UI rename

replace POC with CCX globally

template context variable renamed

rename poc_ to ccx_ in urls and all related locations (views, js, scss etc)

remove pocs migrations

Final massive renaming, including models.  Re-built migration.

cleaning up a few tailing references

Fix reference typo in schedule template JS

undo modifications made on the fly in test setup to ensure that our tests are properly isolated from the rest of the system tests.

Fixes jazkarta/edx-platform#38

Clean up some leftover strings and comments

fixing more strings and comments in python files

fix a naming error in the schedule tab that was causing problems in deleting courseware items.

Fixes jazkarta/edx-platform#36

updating tests and utility code to match changes in infrastructure from latest rebase

This feature provides the ability to designate a "coach" who can create customized runs of an existing course, invite students to participate, and manage students through the run of the course.

In this squashed commit we implement the initial scifi, add the 'POC Coach' course role, refine the scifi, add migrations for models, create POCs, enforce POC Coach role, provide panels for Coach Dashboard, set up rudimentary display of course outline, add and remove units, show/hide all units, and save schedule changes, set dates when adding units, edit dates on units already added and provide some tests.

We also provide mechanisms for invitation and enrollment in a POC (to become CCX) and control the display of blocks to students in a POC.

This reverts commit c2e5bd3d.

individual students, and a reimplementation of the individual due date
feature.

This work introduces an architecture, used with the 'authored_data'
portion of LmsFieldData, which allows arbitrary field overrides to be
made for fields that are part of the course content or settings (Mongo
data).  The basic architecture is extensible by means of writing and
configuring arbitrary field override providers.

One concrete implementation of a field override provider is provided
which allows for overrides to be for individual students.  This provider
is then used as a basis for reimplementing the individual due date
extensions feature as a proof of concept for the design.

One can imagine writing override providers that provide overrides based
on a student's membership in a cohort or other similar idea.  This work
is being done, in fact, to pave the way for the Personal Online Courses
feature being developed by MIT, which will use an override provider very
much long those lines.

Adds an /xdomain_proxy.html endpoint that serves
the proxy file from the xdomain library.  This
allows IE9 users to iframe in the proxy page
to simulate a cross-domain request with cookies.

Adds an /xdomain_proxy.html endpoint that serves
the proxy file from the xdomain library.  This
allows IE9 users to iframe in the proxy page
to simulate a cross-domain request with cookies.

This makes these files importable, and puts them into the new best guess
as to where files should live.

Replaces some PLATFORM_* settings with a more
general setting for specifying social media
URLs in the footer.

Adds icons and titles for new social media
sites (Tumblr, Reddit, Youtube) to match
EdX.org.

Instead of referencing the example externally, we now explain the
setting inline.