Fix json test
Add yaml support
Add yml
YAML
js-yaml doesn't support STDIN.

However, use tmp file to output staged version vs as saved in working dir
Only print coffeelint errors

Unfortunately coffeelint doesn't use STDERR for errors
and instead throws anything on STDOUT.

This is why we color it's STDOUT red.

To avoid okay-messages from being colored red, we just
only show errors.