Upgrade moto to support python3.

Test the django admin view, and that it can be loaded

Since we want anonymous read of these objects, we have to be explicit about
the bucket permissions or the test will fail.

Moto has a vendored version of HTTPretty which also monkey patches the
socket object.  If you activate both, you get weird errors like
https://github.com/spulec/moto/issues/750

So we're opting not to activate both in this test.  We're are just using
the moto vendored version of httpretty for both our usage and the
mocking of boto.

I also removed the logic that seemed like it was just testing that our
mock is a mocking s3 correctly.

They are running into issues because of a bug in moto but looking closer
at what they are testing.  Both tests test the happy path of the
underlying function.  In the happy path scenario all boto calls succeed
and all theses test do is test that but with all the boto calls mocked
out.  So we're just testing whether the mock is a good mock of boto
which is not useful.

Longer term we should move to boto3 in general and then we can use the
default moto mock for s3.

We had to pin json diff because of how we pull prod requirements into
testing.txt

SE-1199 Campus.il Fix unicode username hints with SSO

SE-1155 [Campus.il] fix crashes on non-ascii in usernames for ccx enrollments

* Add optional role parameter to course API endpoint.

* fixup! Add optional role parameter to course API endpoint.

edx-platform version bump

DEPR-15: Remove usage of firebase-token-generator

Update Help msgs of management commands

PROD-399

INCR-405 python3 compatibility

Spanish Help Center Page Update

Added check to only apply the changes for
edx.org help center pages.

Usernames containing unicode characters were
reportedly not showing up correctly in the
registration form when registered with MOE/SAML,
FB and Google.
This change fixes the issue by overriding the
django setting SOCIAL_AUTH_CLEAN_USERNAMES to
disable the default username check that wasn't
allowing non-ascii values.

Previously, unicode would result in a UnicodeEncodeError as a result of
the format string being str instead of unicode.

Additionally, the log calls would crash with a traceback (while not
affecting the program flow).

The old Notes Django app is the only caller of this no longer
supported library. I have verified that this old app is no
longer functional and is already slated to be removed as part
of DEPR-18.

So this commit simply removes the call to firebase-token-generator
and leaves removal of the Notes app to DEPR-18.

DISCO-1222: Allow switching course numbers for reruns

[REVMI-354] add view_ccx_coach_dashboard permission

* REVMI-354 REVMI-356 Revert more masquerade code

* Fix quality

HtmlModule to HtmlBlock [SE-1089]

[REVMI-354] Add preview_certificates permission

* REVMI-354 Add enroll_in_course permission

* Fix test

Changed Spanish language code from es to es-419
modified _build_help_center_url() to receive
selected language instead of default from settings.

Updated Help Center Url

Updated the generated url in the navigation
and footer based on the selected language of
the page.