Module pattern is now implemented via templating

Previously two modules were defined, Layout.js, which is the internal implementation, and main.js, which depended on Layout.js and performed the fill / extract functionality required for a public JavaScript API.

This simplifies the implementation by just exposing a single UMD module by directly including Layout.js within the module wrapper.

Fixes #103

package.json

@@ -20,6 +20,7 @@
     "grunt-contrib-copy": "^0.8.0",
     "grunt-contrib-uglify": "^0.9.1",
     "grunt-eslint": "^17.1.0",
+    "grunt-include-replace": "^3.1.0",
     "grunt-karma": "^0.12.0",
     "jasmine-core": "^2.2.0",
     "karma": "^0.13.8",