Allow Empty Profiles on POST /profiles/:user_id

Courier's POST /profiles/:user_id (profiles.create()) endpoint would accept an empty profile object, return a {SUCCESS: true} but not create the profile. Other endpoints and methods (like .identify() would allow for creating a profile with an empty object. This endpoint was updated to mimic the other endpoints and allow an empty profile to create a user.

Learn more: How to Manage User Profiles