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.
Use /tmp/mako_lms and /tmp/mako_cms for compiled mako templates.

Currently a new temp directory is created for every process via
mkdtemp_clean() which cleans it on process exit.

However, this is not compatible with using --preload option of
gunicorn. With this option the tmp directory is created on gunicorn
start and is shared by all the workers. But when a worker exits it
deletes the directory. And so on the next requent the tmp directory
needs to be recreated and the templates need to be recompiled.

LMS-6507
Update xblock-mentoring.

Update reference to the xblock-mentoring repository.

A bug where answers containing the string "??" would get mangled by jQuery has been fixed in xblock-mentoring.
add initial_state attribute to jsinput tag
Getting draft split_test_module instances to import/export.

STUD-327
Added text about grade ranges and certificates
Merge pull request #4529 from edx/markhoeber-documentation-doc420

Added text about grade ranges and certificates
Merge pull request #4491 from edx/christina/export-split

Getting draft split_test_module instances to import/export.
Release notes for 7-23-2014
Merge pull request #4531 from edx/sylvia/docs/relnotes_7_23

Release notes for 7-23-2014
Make overriding branch settings thread-safe LMS-11125
Merge pull request #4494 from edx/nimisha/request-cache-for-branch-settings

Make overriding branch settings thread-safe LMS-11125
Split branch settings LMS-11056
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
Split branch settings code review fixes LMS-11056
Merge pull request #4532 from edx/split/branch-settings

Split/branch settings LMS-11056
BLD-1110: Create, edit, delete groups.
Add correct_or_past_due option for showanswer and update relevant documentation
Add Martin Segado to authors file
Merge pull request #4480 from edx/anton/create-edit-delete-groups

Group Configuration: create, edit, delete groups