Switch linting to ESLint and Prettier (#191)

* Switch linting to ESLint and Prettier
* Clean up config
* Prettier fixes

lib/is-supported.js

@@ -1,8 +1,12 @@
 module.exports = function() {
   // Borrowed wholesale from https://github.com/defunkt/jquery-pjax
-  return window.history &&
+  return (
+    window.history &&
     window.history.pushState &&
     window.history.replaceState &&
     // pushState isn’t reliable on iOS until 5.
-    !navigator.userAgent.match(/((iPod|iPhone|iPad).+\bOS\s+[1-4]\D|WebApps\/.+CFNetwork)/)
-}
+    !navigator.userAgent.match(
+      /((iPod|iPhone|iPad).+\bOS\s+[1-4]\D|WebApps\/.+CFNetwork)/
+    )
+  );
+};