Add defininition of window.location.origin in both CMS/LMS

The same bug in studio was fixed in #3893, and as TinyMCE is also used in LMS, it should be also fixed in LMS.
Here a common javascript file called 'ie_shim.js' is added, so that in the future it can be used for other IE compatibility purposes too.
Bugfix: Initialize new tabname to "Empty"

In Studio, when the course administrator creates a new tab, its name was being
initialized as null in the mongo database. This caused students in LMS to get a
server error when trying to access the course page, since LMS was trying to
process the null tabname for translation, etc. Now tabname is initialized as
'Empty', which is how it was being done in the frontend.

STUD-2000
Use a version of opaque keys that identifies version numbers in the key prefixes
Make test_export_all_courses do not rely on the order in which files are returned by os.walk().
Disable failing test STUD-2003
Merge pull request #4546 from edx/zoldak/disable-test

Disable failing test STUD-2003
Merge pull request #4474 from Stanford-Online/sjang92/null_tabname_bugfix

Bugfix: New Tab name being initialized as null
Merge pull request #4543 from edx/tim/test_export_all_courses-was-flaky

Make test_export_all_courses not flaky
Merge pull request #4537 from cpennington/new-locator-key-prefixes

Use a version of opaque keys that identifies version numbers in the key prefixes
Unit test for import performance STUD-1994
Refactor studio tests to use StudioCourseTest
Fix is_browser_on_page method for Studio Container page
Merge pull request #4534 from edx/nimisha/import-perf-unit-test-STUD-1994

Unit test for import performance STUD-1994
Use clear and send_keys instead of action chains in page object methods
Merge pull request #4552 from edx/zoldak/studio-container-page

Improve is_browser_on_page method for Studio Container page
removing syslog_addr

This is not currently being used in production and will not
be used moving forward since logs are remoted using splunk
Merge pull request #4558 from edx/jarv/remove-syslog-addr

removing syslog_addr
Merge pull request #4548 from edx/benmcmorran/refactor-studio-tests

Refactor studio tests to use StudioCourseTest
Merge pull request #4557 from edx/zoldak/remove-action-chains

Use clear and send_keys instead of action chains in page object methods
Wrap JSInput Python code in CDATA section

Python code can commonly contain characters that are invalid XML, such
as '<' and '>'. This has proven to be a pain point for instructors
implementing custom Python grading functions for their JSInput problems
(see sample code below).

This change creates a more robust template from which to make
modifications.

```python
    # This is an XML syntax error, when not inside a CDATA section.
    if i < 0:
        print('negative')
```