dillon1000/react

Roll back to babel-eslint 3.1.9

spicyj noticed newer versions of babel-eslint seemed not to error on
no-unused-vars, and I was able to repro. It seems like something broke
between 3.1.9 and 3.1.10. (Smaller repro case and babel-eslint bug
report to come)

His commit failed on travis, but not on his local machine:
https://travis-ci.org/facebook/react/jobs/65468729