Use Prettier JS (#5017)

* Adds prettier

* Run lint before tests

spec/myoauth.js

@@ -2,7 +2,7 @@
 
 // Returns a promise that fulfills iff this user id is valid.
 function validateAuthData(authData) {
-  if (authData.id == "12345" && authData.access_token == "12345") {
+  if (authData.id == '12345' && authData.access_token == '12345') {
     return Promise.resolve();
   }
   return Promise.reject();
@@ -13,5 +13,5 @@ function validateAppId() {
 
 module.exports = {
   validateAppId: validateAppId,
-  validateAuthData: validateAuthData
+  validateAuthData: validateAuthData,
 };