Add /_metadata and /_module functions

Also deprecate ?meta and ?module query params.

modules/server.js

@@ -3,6 +3,8 @@ import express from 'express';
 // import serveAuth from './actions/serveAuth';
 import serveFile from './actions/serveFile';
 import serveMainPage from './actions/serveMainPage';
+import serveMetadata from './actions/serveMetadata';
+import serveModule from './actions/serveModule';
 import servePublicKey from './actions/servePublicKey';
 import serveStats from './actions/serveStats';
 
@@ -49,6 +51,36 @@ app.use(
   })
 );
 
+app.use(
+  '/_metadata',
+  createRouter(app => {
+    app.get(
+      '*',
+      validatePackageURL,
+      validatePackageName,
+      validateQuery,
+      fetchPackage,
+      findFile,
+      serveMetadata
+    );
+  })
+);
+
+app.use(
+  '/_module',
+  createRouter(app => {
+    app.get(
+      '*',
+      validatePackageURL,
+      validatePackageName,
+      validateQuery,
+      fetchPackage,
+      findFile,
+      serveModule
+    );
+  })
+);
+
 app.get(
   '*',
   validatePackageURL,