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.

assets/styles/_variables.less

@@ -0,0 +1,17 @@
+// Grid settings
+// -------------------------
+
+@main-sm-columns:       @grid-columns;
+@sidebar-sm-columns:    4;
+
+
+// Brand colors
+// -------------------------
+
+@brand-primary:         #27ae60;
+
+
+// Glyphicons path
+// -------------------------
+
+@icon-font-path:        "../fonts/";