[0.15.x] suggestion: turn remaining done()/fail() callbacks to promises

[beeplin]

Glad to see in 0.15 many async callback functions have been made to promises, which extremely facilitate the usage of the new async/await syntax.

However I noticed that there are still a few components using done()/fail() callbacks (such as QUpload, QPullToRefresh, QAutocomplete). It would be super nice to make them all promises.