Add API calls for checking workflow completeness
Skip grading/training tasks if the workflow is already complete.
Fallback to file-based cache for classifier data
Add info-level logging for cache hits/misses
Catch HTTP errors that occur when downloading classifier data
Bugfix: validate duplicate point values for rubrics with example-based assessments
Concatenate validation errors with semicolons instead of newlines so they show up correctly in Studio
Update i18n tools version
Pull Transifex strings

Update test scripts to run only eo i18n
Merge pull request #460 from edx/will/transifex-pull

Transifex pull
Merge pull request #454 from edx/will/ai-skip-completed-workflows

Skip completed workflows
Merge pull request #458 from edx/will/TIM-660

Bugfix: validate duplicate point values for rubrics with example-based assessments
Merge pull request #457 from edx/will/TIM-661

Catch HTTP errors that occur when downloading classifier data
Merge pull request #459 from edx/will/TIM-659

Concatenate validation errors with semicolons instead of newlines so they show up correctly in Studio
Merge pull request #456 from edx/will/ai-cache-classifiers-to-disk

AI: Celery workers lose their cache after an exception causing many hits to S3
Changed NLTK requirements from 2.0.3 to 2.0.4
Update wheel archive for NLTK
Merge pull request #461 from edx/grady/NLTK-requirement-change

Changed NLTK requirements from 2.0.3 to 2.0.4
Add criterion foreign key to assessment part model (write only)
Merge pull request #467 from edx/will/assessment-criterion-migration

Add criterion foreign key to assessment part model (write only)
Update placeholder text for student training responses to match current UI
Merge pull request #468 from edx/sylvia/docs/TIM-538

Update placeholder text for student training responses to match current UI
Merge remote-tracking branch 'origin/master' into authoring