REST, get-user should take the :_id of the user (or the email or the username.)

[siscia]

I think that get-user should take the :_id of the user, optionally since also the email and the username are keys of maximal cardinality it could be possible to use also such keys.

[siscia]

The GET request will take as input only the :_id, the other params are not guarantee to stay the same over time, this could lead to confusion from the consumer of the API.