make embargo template theme-able

Use "Stanford-style" theming to enable you to put your own embargo
notice up.
missing themed embargo page fails safely to unthemed
Add SHOW_PROGRESS_SUCCESS_BUTTON feature

Show a button at the top of lms/templates/courseware/progress.html if the
lowest nonzero grade cutoff has been reached. Introduce two settings:
PROGRESS_SUCCESS_BUTTON_URL is the href of that button (the course id is
appended); PROGRESS_SUCCESS_BUTTON_TEXT is the text, defaults to
"Download your certificate"
Make the SHOW_PROGRESS_SUCCESS_BUTTON feature more flexible

The button text default is now in the template and i18n-able, a
PROGRESS_SUCCESS_BUTTON_TEXT_OVERRIDE option is offered in settings.
The button url now uses string formatting.
Add test in import code to make sure two overlapping courses aren't imported
Refactored terminology and added loop break for optimization
Fix missing call to translate in shoppingcart model
Fix missing call to translate for shopping cart btn
Switch PDF Textbooks to use portable URLs
install and set up paver before using it

install and set up paver before using it
pass event to callback functions in membership.coffee (LMS-2547)
Fix missing call to translate in receipt page
Render markup in inline threads on expand/collapse

This was a bug in 3af90ef.
Merge pull request #3389 from edx/hotfix/2014-04-17a

Render markup in inline threads on expand/collapse
Merge pull request #3392 from edx/release

Release
Update bok-choy page definitions
adding django admin command to change enrollment
fixing example
Wording for batch beta email add with autoenroll (LMS-2551)
grammar