Changing default new user password

Due to some security reasons, this patch changes default user assignment
from "same as name" to uuid.

Also, named parameter "password" is removed from method signature.
If there is a need for a new user to be created with preselected
that can be done thru kwargs by seting value with the "password" key.

Change-Id: Iccd085a8e67b204d4f9a985d5628128f4299ff83
Merge "Changing default new user password"