`vulcan:users` runs callbacks with incorrect calling convention

[jimrandomh]

In packages/vulcan-users/lib/server/on_create_user.js, onCreateUserCallback tries to run the same callbacks that createMutator would. Unfortunately, it runs a subtly different set and ordering of callbacks, and omits most of the arguments they would normally be passed.

The right way to do this would be to call createMutator (finding some way to provide a context), sharing code and ensuring matching calling conventions.

[SachaG]

Oh good point. I think I just forgot to change that when I recently cleaned up how mutator callbacks work.

I agree it'd be better to call createMutator, once we refactor Accounts maybe it'll be easier to use the same mutators for users as well.