squash! Add basic PagesController with Devise login requirement

New bullet:

* Restrict 118n version to ensure enforce_available_locales= is
  supported
squash! Add basic PagesController with Devise login requirement

New bullet:

* Restrict devise to ~> 3.3, which is when "Sign in" was changed to
  "Login in" in sessions/new.html.erb.  This is needed for tests to
  pass.