Allow user creation/modification with defined state

What does this MR do?
Extends the attributes with state to allow an user creation/modification via api in predefined state.

Are there points in the code the reviewer needs to double check?
No, the state_machine in Model/User.rb prevent wrong values.

Why was this MR needed?
It is annoying that you can't create or update an user with blocked state instead of active. Sometimes there is a more "complicated" validation process, which requires manual activation or similar.