Replace deprecated electron-prebuilt with electron@2.0.18

- Updated package.json to use electron@2.0.18 instead of electron-prebuilt@1.4.3
- Modified lib/jibo-cli.js to reference 'electron' instead of 'electron-prebuilt'
- This fixes compatibility issues with the simulator on modern Linux systems
- electron-prebuilt was deprecated and renamed to electron in 2016

node_modules/graceful-fs/clone.js

@@ -0,0 +1,23 @@
+'use strict'
+
+module.exports = clone
+
+var getPrototypeOf = Object.getPrototypeOf || function (obj) {
+  return obj.__proto__
+}
+
+function clone (obj) {
+  if (obj === null || typeof obj !== 'object')
+    return obj
+
+  if (obj instanceof Object)
+    var copy = { __proto__: getPrototypeOf(obj) }
+  else
+    var copy = Object.create(null)
+
+  Object.getOwnPropertyNames(obj).forEach(function (key) {
+    Object.defineProperty(copy, key, Object.getOwnPropertyDescriptor(obj, key))
+  })
+
+  return copy
+}