chore(package): update eslint to version 3.12.2
chore(package): update eslint to version 3.12.2

Closes #160

https://greenkeeper.io/

graphql/express-graphql,jamiehodge/express-graphql,wincent/express-graphql,graphql/express-graphql,jamiehodge/express-graphql,jamiehodge/express-graphql,wincent/express-graphql,wincent/express-graphql,graphql/express-graphql