Unify plugins system about assistant

[crisptrutski]

Made any progress with this? I'm thinking along the lines of just live loading the plugins at runtime using something like https://github.com/cemerick/pomegranate.

If you're wanting to pull plugins from git rather than clojars or a maven repo, could reuse hacks from https://github.com/tobyhede/lein-git-deps.

Could support static bundling during build on top of this.

[crisptrutski]

Otherwise, if you're set on pulling JS artifacts instead of source CLJS - maybe something dynamic and flexible like http://jspm.io would be a good fit