Merge pull request #124 from edx/dev

Dev
update to newer version of scipy and matplotlib that don't break on MacOSX 10.8
Add some instructions about installing Xqueue, NLTK data and special instructions for OSX
Refactor staff grading to be easier to follow
Finalize refactor with staff_course
Add docs, fix error message
Fix tests
Final test fix
Centralize capsules (for peer refactor)
Merge pull request #125 from edx/fix/natea/macosx

Fix/natea/macosx
Handling case where 'BC' is latest grader but 'PE' grades exist

This happens in cases where submissions are duplicated
Add tests for staff grading refactor
Randomly shuffle calibration essays to avoid everyone seeing the same sequence
Properly define and use capsules
add tests for BC/PE feedback/grading change
Merge pull request #128 from edx/jbau/edx-west/ora-release

Handling case where 'BC' is latest grader but 'PE' grades exist
Start peer grading refactor
Capsules are no longer properties
Add in tests, clean up property to function conversion
Merge branch 'vik/staff-refactor' into vik/peer-refactor