Feature/victor/nested links

Added class problem-and-answer with margin on the bottom

Make the two buttons that lead to the courseware more actionable

Reduce # of queries for auth checks on Progress page by prefetching user groups

Added styles for problems

OpenID provider implementation

Fix inline html bug.

Feature/victor/fix url name cleanup

Fixing sequentials nested inside of verticals, provides a path to sequentials nested in sequentials. Changes jump_to to redirect to courseware index.

* has to be eager

* it now works in the context of a specific course_id
* add tracking of parent locations to xml modulestore
* adjust lots of tests, including some refactoring
* NOT working yet: jumping to the right position in a sequence.

* add a url that has an extra /{position} at the end
* pass it through to get_module

missing "settings." in line in lms_migration

A gentler, more helpful frontend

Fix discussions in xmodules