chore: Upgrade Babel, Jest, Eslint (#1437)

* chore: Upgrade Prettier 1.8 -> 2.0

* chore: Upgrade Babel 6 -> 7

* chore: Upgrade eslint plugins

* chore: Add eslint import/order rules

* chore: Update flow-typed deps

init.js

@@ -1,4 +1,4 @@
 // @flow
-require("babel-core/register");
-require("babel-polyfill");
+require("@babel/register");
+require("@babel/polyfill");
 require("dotenv").config({ silent: true });