Add about page with feedback functionality

spec/acceptance_steps/users/feedback_steps.rb

@@ -0,0 +1,15 @@
+step "the user fills in the feedback field" do
+  find('.feedback-field').set "Nice app!"
+end
+
+step "the user clicks on the submit feedback button" do
+  find(".submit-feedback-button").click
+end
+
+step "the user should see the feedback submitted message" do
+  page.should have_content I18n.t('user.about.feedback.received')
+end
+
+step "a user feedback should be created containing the feedback" do
+  expect( UserFeedback.find_all_by_user_id_and_content(@user.id, 'Nice app!').size ).to eq 1
+end