Rule tweaks (#6)
Rule tweaks (#6)

- Require parentheses around arrow function arguments. We've mostly standardized
  on this for web code - it's more readable, and harder to confuse with other
  behaviors.
- Move all warnings to errors. We *never* fix warnings, they just serve to make
  the local `make lint` output less readable, and they don't fail builds in CI.
  If there are cases we need `console.log` and friends, we can add one-off
  exceptions using [inline comments](http://eslint.org/docs/user-guide/configuring#disabling-rules-with-inline-comments).
Shyp/eslint-config-shyp