implement Edit user in User.app

Once the user record is highlighted and details are displayed in the rightmost pane, it should be possible to edit the metadata information.

We have talked about two edit modes:

• inline: when a field, or a small icon in the right top corner, is clicked it turns into an input field of matching type, when the field loses focus the update is immediately sent to the server

• form-like with submit: the whole screen is just a form of input fields with pre populated data and there is an explicit submit button at the bottom

Possibly form-like is simpler and we may choose to target it first.

Validations are out of scope for the initial implementation