Return promise in execute function

[mirkoperillo]

At the moment execute function in bookmark module uses callback to manage the response of the call.

Move to promise to have a easier code.

Ref to the code https://github.com/mirkoperillo/resting/blob/f3df3c23238468925c5b1412eab1534f76b08814/src/js/app/request.js#L49