* was going to use to test duplicated content, but we're not supporting that for now

* better error messages
* better fallback names
* architectural TODO for later...

Remove trailing slash from ajax url in ModuleSystem

* also add a check for valid location in modx_dispatch

updated admin_dashboard to show count of unique students

Feature/cale/eagerly load modulestores

commenting out the pre-loading of modules until we get a better way in place (that doesn't hang on deploy)

Allow location url_names to contain ':', mapping to / on file load

Fix latent bug in access checks in get_module

Eagerly load modulestores on server startup

Fix bug with sorting discussion forums 

Feature/rocha/wiki cheatsheet

* New format: {tag}://{org}/{course}/{category}/{name}[@{revision}]
* Updated tests, code
* Added test chapter with : in url_name in toy course
* added test html page with : in url_name
* added a note to docs

Feature/victor/unique names

add manage_course_groups command to lms_migration

* All access checks now done for the "user" param, ignoring request.user
  - This matters for xqueue callbacks and for instructor view of student progress
* An effect of this change is that if a student couldn't see their own 'progress' tab,
  the course instructor won't be able to see it either

fixed a tiny bug that loading icon sometimes doesn't appear at the right place / doesn't go away

Switch django-wiki dependency to a clone in our org

Set request.user = student when impersonating a student

Important fix! Remove HTML tags from Markdown code.

Do URL replacement in course info page

Added a log in button to the courseware when unauthenticated

- only relevant in tests due to start dates
- still irritatingly intricate logic...