Improve custom style syntax

[rickhallett]

Code changed as described in issue #43 .

Code was also formatted by prettier for readability..

[adamschwartz]

Thanks!

One thing we’re going to want to do is make sure we get these changes into the source log.coffee file rather than log.js.

I’m not sure I’m a fan of this syntax yet, so you may want to hold off. Let’s continue our discussion in #43 and see what we can come up.