Get Laravel Dusk installed using PhantomJS so it can work with Travis CI easily

.travis.yml

@@ -38,9 +38,11 @@ before_script:
   - php artisan migrate
   - php artisan db:seed
   - php artisan token:generate
+  - phantomjs --webserver=127.0.0.1:9515 &
   - php artisan serve &
   - sleep 5 # Give artisan some time to start serving
 
 script:
   - phpdbg -qrr vendor/bin/phpunit --coverage-text
+  - php artisan dusk
   - php artisan security:check