[Feature] Allow PUT operations similarly to PATCH requests

[fmigneault]

As of 2.0.0, all PUT requests that previously provided partial update of an object are changed to PATCH (as they should according to REST method definition).

On the other hand, we could still support PUT *if an only if the full object details are provided in the body.

For example, user creation (POST) requires user_name, password, email and (optionally) group_name.
Requesting PUT with all those parameters should allow overwrite of the details.

Obviously, necessary user-access to operations would need to be validated accordingly.
With same example, user_name cannot be updated by non-admin. Therefore, PUT should be an admin-only operation because the user_name must be provided and (possibly) changed.