Rename submodule fetch to network

PR-URL: #92

Author: tshemsedinov

lib/fetch.js lib/network.jslib/fetch.js renamed to lib/network.js

@@ -6,5 +6,5 @@ module.exports = {
   ...require('./lib/semaphore.js'),
   ...require('./lib/pool.js'),
   ...require('./lib/async.js'),
-  ...require('./lib/fetch.js'),
+  ...require('./lib/network.js'),
 };