Add ADDL_INSTALLED_APPS to studio for parity with lms
Added trailing slashes otherwise the course_id regex sometimes eats up get parameters.

LMS-2738
BLD-725: ChoiceGroup i18n.
Extract opaque_keys into a separate library

[LMS-2571]
Fix exception on Internet Explorer when adding first transcript language

Internet Explorer throws an "Invalid argument" exception when uses an empty string as the parameter in ```namedItem``` method.
Change empty string into null value can maintain browser consistency.
Do not persist anonymous ids when exporting for all students of a course.

For large courses this causes export to take a long time and to time out.

LMS-2747
Allow courses to set Matlab API key globally, in advanced settings.
Updated payload for new matlab endpoint.
DOC-362, another set of students who don't get email
Moved hardcoded defaults into settings
Don't hardcode https protocol in enrollment emails.

Use http or https, depending on the value of `request.is_secure()`.
That is how links in most other emails are handled.
Fixes some stuff in metrics tab
  Fixes some 500s after opaque-keys
  Adds a test which would have caught the 500s
  Fixes Transifex problem on the string % of students
Build 'window.location.origin' for Internet Explorer

As TinyMCE's CodeMirror plug-in uses 'window.location.origin' which is not supported by Internet Explorer, the HTML or raw code editor does not work under Internet Explorer.
We need to create one in order to make these vendor codes work under Internet Explorer.
BLD-1103: Fix ChoiceTextResponse.
Merge pull request #3902 from edx/anton/i18n-choice-group

ChoiceGroup  i18n.
Merge pull request #3879 from edx/usman/lms2747-anonymous-ids-collection

Do not persist anonymous ids when exporting for all students of a course.
Merge pull request #3833 from edx/usman/lms2738-verify-student-urls

Added trailing slashes to verify_student app urls.
Ensure no old gems are left behind between test runs.
JavascriptResponse i18n. [BLD-737]
Merge pull request #3918 from edx/jmclaus/i18n-javascript-response

JavascriptResponse i18n.