Move Makefile into nbviewer
Merge pull request #136 from rgbkrk/movement

Move Makefile into nbviewer directory/package
Merge pull request #134 from minrk/mcpool

memcache adjustments, threading, etc.
use 'slow page' template when notebooks are slow

original request will finish, it will just never write to the client,
only the cache.

should avoid heroku timeout errors
short circuit redirect in finish_early