Switched to eslint

Not sure if you want to bump this to 0.7.x. I have eslint 0.7.4 installed globally and this passes `make lint` (using local 0.6.x) but fails if I use my newer global version of eslint:

```sh
$ eslint config loop test

test/middlewares_test.js
  78:1  error  Unexpected blank line at end of file  eol-last

✖ 1 problem
```