Revisions to ai grading arch doc
Updating a validation message.
Merge pull request #312 from edx/will/ai-grading-arch-revisions

Revisions to ai grading arch doc
Merge pull request #314 from edx/sanchez/fix-validation-message

Updating a validation message.
added markupsafe for requirements
Move peer assessment private methods into models.
Move errors for assessment app into a module.
Merge pull request #315 from edx/markhoeber/documentation/requirements-fix

Added markupsafe for requirements
Merge pull request #316 from edx/will/refactor-peer-api

Peer API Refactor
Remove option to disable over-grading
Merge pull request #317 from edx/will/remove-overgrading-option

Remove option to disable over-grading
Split models.py into separate Python modules
Merge pull request #318 from edx/will/assessment-package-refactor

Split models.py into separate Python modules
Adding the ability to review a single student as staff