Merge pull request #122 from twokul/master

Support standard CSS
Edited asset docs & removed redundant comments
I am bad at VIM.
document compass gem
Fix typeof-array-check
Merge pull request #140 from fpauser/helpers_fix

Fix typeof-array-check
removed unused/confusing public/assets/app.css file
concat_css => cssmin
Merge pull request #142 from jmonster/master

concat_css => cssmin
Run compile tasks concurrently
Replace whenAvailable with filterAvailable
Replace defaultConfig with mutable config object
Merge pull request #134 from mbixby/feature/concurrent

Concurrent compilation
Merge pull request #143 from mbixby/feature/filter-available-task

Replace whenAvailable with filterAvailable for simpler configuration