Reorganizes asset file structure

Separates assets into
- Source assets: `assets`
- Compiled assets: `dist`

Edits assets.php to reflect changes

Removes '.min' from filenames

Fixes:
- removes 'clean' from build step.

.gitignore

@@ -1,5 +1,5 @@
 # Include your project-specific ignores in this file
 # Read about how to use .gitignore: https://help.github.com/articles/ignoring-files
-assets/dist
+dist
 bower_components
 node_modules