Provide a Package that Spacemacs Can use in additional-packages

[erichlf]

If I attempt to install google-calendar-layer the "proper" way in spacemacs, i.e.

      (google-calendar :location (recipe
           :fetcher github
           :repo "mhkc/google-calendar-layer"))

under additional-packages and then under user-config put (require 'google-calendar) I get an error saying that the package couldn't be loaded due to a missing google-calendar.el file. This method requires that a google-calendar.el file exists and in that file (provide 'google-calendar) exists. There may be some more details, but that is as far as I have gotten so far.