Fix certs regenerate_user for OpaqueKeys

Squashing commits

Transition to Oqaque Keys

Bug fixes

Fixing regenerate_user
Move research message below normal text
Instructor API endpoint: IRC auth token

Adds /instructor/api/irc_instructor_auth_token API endpoint which
returns a JSON blob including a per-course magic key iff the logged-in
user is an instructor in the course.
Deny self-service certificates for anonymous users

Bugfix for the following condition:
When anonymous (e.g., non-registered) access is enabled for a course,
and that course also uses the /request_certificate endpoint (e.g., via
the "Grade Me" button), anonymous users could request to be graded and
given certificates.

As a matter of policy, Stanford doesn't want to give certificates to
anonymous students.

Also adds defensive error checks in several more places.
Limit sneakpeek middleware from acting on API-like request

Impose the following restrictions on setting up sneakpeek
* Has to be a GET
* Cannot be a machine callback to handler from xqueue or xblock
* Cannot be trying to list the LTI endpoints
pin LTI scores to 2 decimal places
Merge pull request #57 from Stanford-Online/jbau/lti-precision-master

pin LTI scores to 2 decimal places
Allow <img> tags in LTI2.0 feedback
Merge branch 'rc'

Release on 2014-06-26
Merge pull request #59 from Stanford-Online/jbau/lti-allow-images-in-feedback

Allow <img> tags in LTI2.0 feedback
Added caption utility to checklist for Instructors