- for now, wraps existing render functions as separate classes
- a bit of cleanup in how it's called from capa_problem
- initial tests to make sure things are testable.

- give different errors when student or author stuff is messed up (I was seeing "No way to interpret '3' as a number" :P)
- preserve traceback in exception

* Move tests into a separate file
* add a chemical_equations_equal function to compare equations, not expressions
* rename some internal functions with a leading _

- needed for chemical equation parsing, which is about to appear in capa

- move progress tests into test_progress.py
- move grader tests into test_graders.py
- move the capa tests into capa/tests/

Victor/capa cleanup

Looks good.  Yes, the code exec part will need more thought, particularly with respect to security.

Don't want to break existing problems.

This reverts commit 811422a1.

- check for known script type instead of ignoring js and perl

Added starting_index conf to AssignmentFormatGrader.

Added starting_index conf to AssignmentFormatGrader. Added a bit of forwards compatibility for new grading policies.

added ie warning banner to courseware; displayed by ie conditional style...

Set git push.default to current on the create-dev-env script

Fix error when creating empty associations

move output right/wrong image to top left of each test instead of center

Also renamed some variables to make them more distinguishable

Use django cache for OpenID provider store

changed vote button icon display mode to fight zoom bugs

added google analytics to all pages without a course object

Fix create-dev-env script for Mac OS 10.8 and latest stable rvm

Add support for video download link

Replaced the previous method of getting it from HTTP_POST to use
django's mechanism, which may or may not use HTTP_HOST. However if an
attacker changes the request header, there is not much he can do since
he cannot recreate the association nonce.