Pass `--load-images=no` to PhantomJS via Capybara/Poltergeist

We were unintentionally hitting `gravatar.com` whenever a test that used
Poltergeist was run. This was certainly wasting their resources and
slowing down our tests even further, for no reason.

features/support/capybara.rb

@@ -6,7 +6,15 @@ timeout = (ENV['CI'] || ENV['CI_SERVER']) ? 90 : 15
 
 Capybara.javascript_driver = :poltergeist
 Capybara.register_driver :poltergeist do |app|
-  Capybara::Poltergeist::Driver.new(app, js_errors: true, timeout: timeout, window_size: [1366, 768])
+  Capybara::Poltergeist::Driver.new(
+    app,
+    js_errors: true,
+    timeout: timeout,
+    window_size: [1366, 768],
+    phantomjs_options: [
+      '--load-images=no'
+    ]
+  )
 end
 
 Capybara.default_max_wait_time = timeout

spec/support/capybara.rb

@@ -7,7 +7,15 @@ timeout = (ENV['CI'] || ENV['CI_SERVER']) ? 90 : 10
 
 Capybara.javascript_driver = :poltergeist
 Capybara.register_driver :poltergeist do |app|
-  Capybara::Poltergeist::Driver.new(app, js_errors: true, timeout: timeout, window_size: [1366, 768])
+  Capybara::Poltergeist::Driver.new(
+    app,
+    js_errors: true,
+    timeout: timeout,
+    window_size: [1366, 768],
+    phantomjs_options: [
+      '--load-images=no'
+    ]
+  )
 end
 
 Capybara.default_max_wait_time = timeout