Update ddt to 0.8.0
Clean up logging in peer and self assessment mixins
Catch a peer API workflow exception
Merge pull request #391 from singingwolfboy/db/update-ddt

Update ddt to 0.8.0
Remove cache key versioning
Merge pull request #401 from edx/will/remove-cache-key-version

Remove cache key versioning
Merge pull request #392 from edx/will/log-peer-request-error

Clean up logging in peer and self assessment mixins
Merge branch 'master' into ai-grading