[cli] Remove data option type and add new tagged option concept.

[cli] Remove data option type and add new tagged option concept.

  * Supported option types are boolean, number and string. Boolean
    options are pure tags like '--no-color'. Number and string options
    maybe tagged like '--proxy-url http://example.com' or just pure
    values like 'username' or '42'.

Signed-off-by: Matthias Bolte <matthias.bolte@googlemail.com>