Remove fs-extra dependency

server/libs/universalify/LICENSE

@@ -0,0 +1,20 @@
+(The MIT License)
+
+Copyright (c) 2017, Ryan Zimmerman <opensrc@ryanzim.com>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the 'Software'), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

server/libs/universalify/index.js

@@ -0,0 +1,24 @@
+'use strict'
+
+exports.fromCallback = function (fn) {
+  return Object.defineProperty(function (...args) {
+    if (typeof args[args.length - 1] === 'function') fn.apply(this, args)
+    else {
+      return new Promise((resolve, reject) => {
+        fn.call(
+          this,
+          ...args,
+          (err, res) => (err != null) ? reject(err) : resolve(res)
+        )
+      })
+    }
+  }, 'name', { value: fn.name })
+}
+
+exports.fromPromise = function (fn) {
+  return Object.defineProperty(function (...args) {
+    const cb = args[args.length - 1]
+    if (typeof cb !== 'function') return fn.apply(this, args)
+    else fn.apply(this, args.slice(0, -1)).then(r => cb(null, r), cb)
+  }, 'name', { value: fn.name })
+}