Add support for subtitle download link

Taking out MySQL-python for now because it requires mysql to be installed, so breaks updates on content folks' envs.

revert to using getElementsByClassName in .dialog b/c jQuery was

undefined on the content passed in & whole widget is disabled in ie8.

Feature/alex/doc

add doc file about use of mongo (by cms+lms)

merge to master

debug fns from per problem to part of courseware w/ context info passed
as parms. Known issues: ie8 complains that getlog is not defined if you
click on QA and does not show the debug info popup.

Remove openings from job page

Use one of our test courses when testing course permissions for the discussion client

Use one of our test courses when testing course permissions for the discussion client, because we now have course policy level overrides.

Fix a bug with pointer-tag detection on load

if a tag has text but no children, wasn't properly detected as an inline definition.

Remove learning designer and producer openings from job page

Fixed install by adding mysql

More inputtype refactor …

- change a few comments / strings
- move extract_choices into the ChoiceGroup class

Fix alex vsepr 2 mitx

Fixed dependency problem introduced by MySQL-python by forcing distribute version >= 0.6.28 in pre-requirements

Added DEBIAN_FRONTEND=noninteractive to sudo apt-get which is required for silent mysql-server installation

Support blackout periods for restricting student forum posts per class