TravisCI: bundle all gems. Use poltergeist/phantomjs

.travis.yml

@@ -1,6 +1,6 @@
 language: ruby
 cache: bundler
-install: bundle install --without development --deployment --jobs=3 --retry=3
+install: bundle install --jobs=3 --retry=3
 cache:
   directories:
   - vendor/bundle

spec/spec_helper.rb

@@ -34,7 +34,7 @@ RSpec.configure do |config|
 
   config.before(:each) do
     if example.metadata[:type] == :feature
-      Capybara.current_driver = :selenium
+      Capybara.current_driver = :poltergeist
     else
       Capybara.use_default_driver
     end