Ensure Backbone sync uses "create" method on sign-in.
Ensure Backbone sync uses "create" method on sign-in.

+ Default `id` caused "update" instead of "create"
  because `user.isNew()` returned false.

teikei/teikei,sjockers/teikei,sjockers/teikei,sjockers/teikei,teikei/teikei,teikei/teikei