Add login & user tests

spec/features/contest_spec.rb

@@ -5,10 +5,7 @@ RSpec.feature "Contests", type: :feature do
     let!(:user) { create(:user) }
 
     before do
-      visit '/'
-      fill_in "Email address", with: user.email_address
-      fill_in "Password", with: user.password
-      click_button "Sign in"
+      login(user)
     end
 
     it "should display the username" do