Implement authentication

[marlabrizel]

Using the Rails docs for secure password control, implement authentication for the application so that the following test passes:

# test/system/movies_system_test.rb

test "members can log in and be greeted by name" do
  member = create(:member, password: "password", password_confirmation: "password")

  visit movies_path

  click_link "Log In"

  fill_in :email, with: member.email
  fill_in :password, with: "password"

  click_button "Submit"

  assert_text member.email
end