Cache remote checks on proofs.

Just a proof of concept for now.  Needs more configuration.
See Issue #35

Squashed commit of the following:

commit 693541298c7bfca1823c76072f87789a7c725fd1
Author: Maxwell Krohn <themax@gmail.com>
Date:   Sat Oct 25 16:18:06 2014 -0400

    display when cached, maybe overkill, but keep for now

commit 41c19e4ee3fd299e8d116ff64c3562d50fa14cfb
Author: Maxwell Krohn <themax@gmail.com>
Date:   Sat Oct 25 16:13:10 2014 -0400

    enable turning off cache if we want to

commit 45affea77f8a5804d921183c537fa67b0d872683
Author: Maxwell Krohn <themax@gmail.com>
Date:   Sat Oct 25 16:12:03 2014 -0400

    report if it was cached

commit 634d67bb62172ff694524f3e7b7d269eb1b901ae
Author: Maxwell Krohn <themax@gmail.com>
Date:   Sat Oct 25 15:24:46 2014 -0400

    caching seems to work!

commit c87e91824ff5e233432645eb99aee4cf308c4ee8
Author: Maxwell Krohn <themax@gmail.com>
Date:   Sat Oct 25 15:00:05 2014 -0400

    progress on proof caching

commit 07762adf4395500d388c6eeb80aac4825d8f5756
Author: Maxwell Krohn <themax@gmail.com>
Date:   Sat Oct 25 14:05:17 2014 -0400

    hacking around on proof cache stuff