Point xblock SDK back to the tip of master
Merge pull request #290 from edx/will/fix-xblock-sdk-pointer

Point xblock SDK back to the tip of master
Revert "Renaming feedback to comments for a peer assessment."

This reverts commit 73df4fa7ecfe7284a34a736194223aa8221ff754.
Fix the Grading Completed At timestamp logic.
Merge pull request #291 from edx/sanchez/revert_comments_naming

Revert "Renaming feedback to comments for a peer assessment."
Merge pull request #292 from edx/sanchez/fix_grading_completed_at

Fix the Grading Completed At timestamp logic.
Backend changes to support feedback per criterion.
Add XML option to allow feedback on criteria
Remove unused start/due date args in xml parsing
Placeholder template for feedback on criterion