skip tests if not run in lms

fix other various i18n issues

Remove course_from_id
don't fetch whole course when the root will do
don't fetch even the root if the id will do
check for definition.data == null

LMS-2734

[LMS-2757]

This reverts commit 59e3cae4.

Makes small changes in lms and cms both so that user's go to the
original page they intended to if they weren't already logged in

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]

* API endpoint for certificate generation, an authenticated  post with course
  id requests that grading be carried out and a cert generated for
  request.user in that course, using the usual grading and certificate
  machinery (ie, it does not imply whitelisting, though whitelists and
  blacklists will be respected)
  - Logs each request as it comes in
  - Calls xq.add_cert() and consequently, does grading synchronously on
    this app host and then queues request for certificate agent.
  - example usage:
    ```
    curl --data "student_id=9999&course_id=Stanford/2013/Some_Class" http://127.0.0.1:8000/request_certificate
    ```

* Studio advanced setting added, "certificates_show_before_end", which
  determines whether a course should permit certificates to be downloadable
  by students before the coures's end date has passed.
  - Modifications to dashboard view and templates to allow display of
    certificate download links before course has ended.
    (XXX: may declare failing students as failing before the course has ended.)
  - To test, turn the setting on in a course which hasn't ended yet, and
    force certificate generation for a student, then check their
    dashboard.

LMS-2479

LMS-2442

Add some optional policies around password resets, such as password reuse, forced password resets, allowed frequency of password resets

Also improves handling in cases where account creation did succeed, but
comments service user creation did not.

Depends on commit 88abdd8a0b20bc9816f487b25abdea1953f5661d in https://github.com/edx/cs_comments_service

JIRA: FOR-522

This is necessary to allow non-browser-based services (e.g. notifier)
to know a user's preferred language even if the user has not explicitly
selected one.

Use "Stanford-style" theming to enable you to put your own embargo
notice up.

Allows specification of countries to embargo, what course(s) should
apply embargo restrictions, and whitelist/blacklist capability for
specific individual IP addresses.

Adds configurable middleware in common/djangoapps/embargo that
allows specific courses to comply with US Export regulations by
embargoing students from specific countries, whilst simultaneously
allowing other courses to be freely open to all.

JIRA: FOR-472

LMS-1479