Add ?module support for HTML files

Closes #113

modules/utils/rewriteBareModuleIdentifiers.js

@@ -0,0 +1,23 @@
+const babel = require("babel-core");
+
+const unpkgRewrite = require("../plugins/unpkgRewrite");
+
+function rewriteBareModuleIdentifiers(code, packageConfig) {
+  const dependencies = Object.assign(
+    {},
+    packageConfig.peerDependencies,
+    packageConfig.dependencies
+  );
+
+  const options = {
+    // Ignore .babelrc and package.json babel config
+    // because we haven't installed dependencies so
+    // we can't load plugins; see #84
+    babelrc: false,
+    plugins: [unpkgRewrite(dependencies)]
+  };
+
+  return babel.transform(code, options).code;
+}
+
+module.exports = rewriteBareModuleIdentifiers;