Try using headless chrome for integration tests

.travis.yml

@@ -3,9 +3,6 @@ sudo: required
 dist: trusty
 addons:
     chrome: stable
-before_script:
-  - "export DISPLAY=:99.0"
-  - "sh -e /etc/init.d/xvfb start"
 node_js:
 - 6
 cache:

test/helpers/selenium-helper.js

@@ -34,8 +34,11 @@ class SeleniumHelper {
     }
 
     getDriver () {
+        const chromeCapabilities = webdriver.Capabilities.chrome();
+        chromeCapabilities.set('chromeOptions', {args: ['--headless']});
         this.driver = new webdriver.Builder()
             .forBrowser('chrome')
+            .withCapabilities(chromeCapabilities)
             .build();
         return this.driver;
     }