ORA2 (openassessment) problems have multiple dates associated with are
not bound to the `due` date that is modified by Personalized Learner
Schedules. We expose the ORA2 dates separately in the dates page
so that learners aren't surprised by the differing deadlines.
[AA-223]
- set up util function to use Amazon SES for sending calendar
sync emails.
- remove old sailthru code which we originally implemented for
this functionality
- include ADR on our decision to use SES instead of Sailthru.
This is an unused-as-of-yet utility function to generate a bunch
of ics files for a user's course schedule. Will be used as part
of the calendar_sync feature package.
AA-37
