add scroll to top on vertical view change
add jasmine test for scroll to top
i18n: submit buttons at dashboard
i18n: staff/student toggle link
i18n: problem submit buttons.
Improve accessibility for forums post toolbar

Mark toolbar and buttons with appropriate ARIA roles, add them to the
tab order, and make the titles more screen-reader friendly.
Consider redirect code as succcesful
Link to How To Contribute wiki page

Created a CONTRIBUTING.rst which GitHub will pick up and included a
link to the How To Contribute wiki page there. Also added the same link
to the README in the "How To Contribute" section.
Moved to a more comprehensive contributing doc.

Based on the How To Contribute wiki page (and switched to markdown so
it's a simple copy-paste).
Link to wiki with absolute URLs
Added linebreaks.
Properly handle error responses
Prompt before leaving page
Don't try to purchase the same order twice
Catch IOError and ignore if OS X companion file
Remove useless try-except clause
don't remove comments from xml module
Fix import errors with unicode filenames
Add tests for imports with unicode filenames
Fix unicode errors on exceptions and logging