Added support for 409 Conflict, and refactored API error handling.
Added support for 409 Conflict, and refactored API error handling.

mozilla/moztrap,mccarrmb/moztrap,bobsilverberg/moztrap,mozilla/moztrap,mccarrmb/moztrap,bobsilverberg/moztrap,mccarrmb/moztrap,mozilla/moztrap,mccarrmb/moztrap,shinglyu/moztrap,shinglyu/moztrap,mccarrmb/moztrap,mozilla/moztrap,shinglyu/moztrap,shinglyu/moztrap,mozilla/moztrap,bobsilverberg/moztrap,bobsilverberg/moztrap,shinglyu/moztrap