Refactored staff debug info to use decorators for permissions checks
Added classifier info to staff debug section
Catch connection refused errors and improve display message
Cleaned up staff debug XBlock tests
Merge pull request #440 from edx/will/staff-debug-classifier-info

Classifier info in staff debug
Avoid duplicate work when grading with EASE
Add script to benchmark EASE.
Cache classifier data
Merge pull request #431 from edx/will/optimize-ease

Will/optimize ease
Merge pull request #433 from edx/will/ai-cache-classifiers

Cache AI classifier data
Update Travis script to install numpy/scipy/scikit/nltk
Add classy AI algorithm