Add tests for submission step rendering
Add unavailable state for submission step

Refactor save status context

Refactor date format
Update the due date parsing script to display properly.

Conflicts:
	apps/openassessment/xblock/peer_assessment_mixin.py
	apps/openassessment/xblock/self_assessment_mixin.py
Merge pull request #260 from edx/will/submission-unavailable-2

Submission step unavailable and Display Timezone UTC