TNL-2321

- Remove grader(s) upon deletion of existing entrance exam
- Remove grader(s) upon addition of new entrance exam

Conflicts:
	common/lib/xmodule/xmodule/xml_module.py

When people use unicode course org name(e.g Chinese) ,urllib.quote cannot format unicode char like:

```shell
>>> import urllib
>>> loc = 'i4x://创联/7302478/chapter/4ab413b41ad9447db41668bed03f149f'
>>> urllib.quote(loc)
'i4x%3A//%E5%88%9B%E8%81%94/7302478/chapter/4ab413b41ad9447db41668bed03f149f'
>>> urllib.quote(unicode(loc))
Traceback (most recent call last):
  File "<console>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 6: ordinal not in range(128)
>>>
```
so I open this pull

SOL-1, SOL-2, SOL-3

STUD-1726

STUD-1707

STUD-1754

Refactor get_parent_locations STUD-1663

This commit implements STUD-1490, allowing creation of components
on the container page. It also enables the delete and duplicate
buttons now that new content can be created that would benefit.

Note that it also creates shared functionality for adding components,
and refactors the unit page to use it too.

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]

This is the changes for STUD-1244, which introduces the ability for Studio to display
arbitrarily nested xblocks. In this change, a new container page is introduced which can
display nested xblocks. In particular, the xblock type of 'vertical' is special cased
to be shown inline as a collapsible section. The unit page is mostly unchanged, except
that container xblock's are shown as a link to their container page, rather than being
shown inline.

This has caused confusion, since this file gets imported when trying to
import the requests library.  And besides, how was this file about
requests in the first place?  Helpers is a much better name.

resets the cms edge redirect to '/'

resets the cms edge redirect to '/'

Remove unused course_filter page

removes university_profile urls and templates

removes all university_profile views

remove news from templates/index

Replacing the get_request_method function everywhere