507 advanced opts again

Functionality is generally fine on my end. Could you help make sure?
Closes #507 if merged.

My process: run `lein cljsbuild auto prod` in a terminal, touch a cljs file so compilation runs, wait for compiler to run, and then refresh my pages. If you view the network tab on chrome, our main.js should be something like 600KB, and ~160KB zipped, rather than 2.9MB and 400KB zipped.

Ie,
![screen shot 2014-10-28 at 3 07 59 pm](https://cloud.githubusercontent.com/assets/178868/4806574/afc4a602-5e8a-11e4-9a7d-47bcf383a3c1.png)
rather than
![screen shot 2014-10-28 at 3 06 25 pm](https://cloud.githubusercontent.com/assets/178868/4806575/b18c01e2-5e8a-11e4-9f28-c9d8e57e0f21.png)


I think the empty list ```[ ]``` can be removed as one of the arguments as it will default to nil if not provided.