fixup! Make Studio support opaque-keys
fixup! Make Studio support opaque-keys
fixup! fixup! Fix all uses of UsageKeys and CourseKeys, and all of their tests.
fixup! Fix all uses of UsageKeys and CourseKeys, and all of their tests.
fixup! Fix all uses of UsageKeys and CourseKeys, and all of their tests.
Merge pull request #3400 from edx/fhrebase/opaque-keys

fixup! Fix all uses of UsageKeys and CourseKeys, and all of their tests.
fixup! Fix all uses of UsageKeys and CourseKeys, and all of their tests.
fixup! fixup! Fix all uses of UsageKeys and CourseKeys, and all of their tests.