Split the Diff factory into two stages... build and execute
This will give us the opporunity to better communicate to users exactly what is going on. It'll also make it possible to work with a real work queue, if that is ever desired.

Added seed, which gets loaded into the repl, and serves as a place to programmatically create a bit of data for to test on. run it with seed(controllers)

Still hoping I can find a way to get bunyan to play nice with the repl. it's terribly ugy otherwise.