Add ContextResult and error tracking

Add a ContextResult object with an error flag and a results iterator.

Also switch processor to use an AsyncResult...


What do you guys think?

@robertkluin-wf @tannermiller-wf @johnlockwood-wf @rosshendrickson-wf
Dammit, I only did string replace on this in one file. I apparently can't spell that at all.