Switching template rendering to use Handlebars

- Extracting the IE8 notice and SVG templates out into partials
- Moving changelog details into a data file

lib/helpers/layouts.js

@@ -0,0 +1,5 @@
+var layouts = require('handlebars-layouts');
+
+module.exports.register = function(handlebars) {
+  layouts.register(handlebars);
+};