refactor tests and babel config. Fixes target browsers.

This is basically the change propagated from the current
default preact tempalate. Now the code compiles according to set
browsers.

tests/footer.test.js

@@ -0,0 +1,12 @@
+import { h, Component } from 'preact';
+import Footer from '../src/components/Footer';
+import { Link } from 'preact-router/match';
+// See: https://github.com/mzgoddard/preact-render-spy
+import { shallow, deep } from 'preact-render-spy';
+
+describe('Initial Test of the Footer', () => {
+	test('Footer renders 1 link with an ID of notificationsBtn', () => {
+		const context = shallow(<Footer prefs={{}} />);
+		expect(context.find('#notificationsBtn').exists()).toBeTruthy();
+	});
+});