Attempt task recovery through callback and confirmation or continuation prompt

[colindean]

A few of my users reported accidental hang-ups. It'd be great if callpower would call back a user who hangs up before they've completed their calls. The callback would prompt to continue. The user could be instructed simply to hang up to give up or press star to continue. If they press star and then hang up at any point before completion, callpower tries recovery again.