Let npm reorder package.json

This is how it looks after running "npm install --save-dev".
Add and configre ESLint for JavaScript linting

Unlike the more well-known JSHint, ESlint is under a proper free
sofware license.
ESLint: don't check for unused function arguments

This allows us to declare functions (in particular callbacks) using
the full function signature, even when we don't actually use all the
provided arguments.
ESLint: add missing semicolons
ESLint: always use curly braces with if-statements
ESLint: add spaces around infix operator
ESLint: remove dangling commas
ESLint: always use strict mode
ESLint: allow the use of "=="
travis: add eslint to the test script
Merge pull request #12 from mgeisler/eslint

Add ESLint to devDependencies and configure it