fix linter issues

Author: solkimicreb

.babelrc

@@ -1,3 +1,3 @@
 {
-  "presets": ["react", "es2015", "es2017", "stage-0"]
+  "presets": ["react", "es2015", "stage-0"]
 }

__tests__/Clock.test.js

@@ -6,7 +6,7 @@ import App from '../examples/clock/App'
 
 describe('Clock App', () => {
   const clock = sinon.useFakeTimers()
-  const app = mount(<App/>)
+  const app = mount(<App />)
   const clearIntervalSpy = sinon.spy(global, 'clearInterval')
 
   afterAll(() => {

__tests__/Contacts.test.js

@@ -4,7 +4,7 @@ import toJSON from 'enzyme-to-json'
 import App from '../examples/contacts/App'
 
 describe('Contacts App', () => {
-  const app = mount(<App/>)
+  const app = mount(<App />)
 
   test('should add new contacts', async () => {
     expect(toJSON(app)).toMatchSnapshot('01. Initial state')

__tests__/TodoMVC.test.js

@@ -4,7 +4,7 @@ import toJSON from 'enzyme-to-json'
 import App from '../examples/todoMVC/App'
 
 describe('TodoMVC App', () => {
-  const app = mount(<App/>)
+  const app = mount(<App />)
 
   test('should add todos', async () => {
     expect(toJSON(app)).toMatchSnapshot('01. Initial state')