chore(build): Migrate remaining tasks under build.js.dev to broccoli.

tools/broccoli/html-replace/index.js

@@ -0,0 +1,10 @@
+var fs = require('fs');
+var path = require('path');
+
+module.exports = read;
+function read(file) {
+  var content = fs.readFileSync(path.join(__dirname, file + '.html'), {encoding: 'utf-8'});
+  // TODO(broccoli): we don't really need this, it's here to make the output match the tools/build/html
+  return content.substring(0, content.lastIndexOf("\n"));
+}
+