chore(travis): use Firefox 47 for protractor tests

Browserstack is unused, but I still updated it

Author: Narretz

protractor-travis-conf.js

@@ -13,7 +13,7 @@ if (process.env.BROWSER_PROVIDER === 'browserstack') {
     }),
     capabilitiesForBrowserStack({
       browserName: 'firefox',
-      version: '28'
+      version: '47'
     }),
     capabilitiesForBrowserStack({
       browserName: 'safari',
@@ -33,7 +33,7 @@ if (process.env.BROWSER_PROVIDER === 'browserstack') {
     }),
     capabilitiesForSauceLabs({
       browserName: 'firefox',
-      version: '28'
+      version: '47'
     }),
     capabilitiesForSauceLabs({
       browserName: 'safari',