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.
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')
```
Merge pull request #4392 from louyihua/lms-window-origin

Add defininition of window.location.origin in both studio and LMS
Add edit info to instantiated xblock in update_item
Refactor to use usage_key_with_run in item.py
Merge pull request #4563 from Stanford-Online/stv/jsinput/cdata

Wrap JSInput Python code in CDATA section
Merge pull request #4544 from edx/benmcmorran/fixes-from-bulk-publishing

Return edit info from update_item and refactor item.py to use usage_key_with_run
Use data dir from course.