Wrap all assessment and part creation in a single transaction
Merge pull request #593 from edx/sanchez/wrap-assessments-in-transactions

Wrap all assessment and part creation in a single transaction
Avoid creating duplicate workflow items

Conflicts:
	openassessment/xblock/static/js/openassessment.min.js
Update minified JS
adding a new unit test to verify the correct number of peer render calls
Updating workflow item 'find' functions to exclude duplicate items