An integrity error while creating an enrollment just means that our work has already been done. Fixes https://www.pivotaltracker.com/story/show/46915947

strings.

Added unit tests that verify the fix.

When a user logs in this will drop a new cookie 'edxloggedin' that will
match the value and expire date of the django session cookie.
When a user logs out the cookie will be removed

Switch timed_module to store location, and use to navigate from timer when timer displays on non-exam course pages.

If certificate status is 'restricted' the grade
and survey link will be shown, the download link will not

This reverts commit dcc53c2b.

* renaming login to login_user
* renaming register to register_user

If there is no announcement date (in the policy metadata) then use a
heuristic to sort them.

If there is an announcement date, the use it in the heuristic to
determine if the course is new or not.

Add some log statements. Add missing fields to _make_tc_user, and make _make_tc_registration independent of course configuration (for testing)