Support customization of the unshortening step.

This should make it possible to test this thing, I think.
Add incomplete spec for Expandr.Core.
merge branch 'testable'.

it's oldish, but ok, i think.
fix build.

ghc-7.8, scotty was updated, network-uri was missing from dependencies.
fix scotty version.

that should work? not sure, would be cool if there was a command that
does that, but doesn't freeze everything. there's `cabal-build`, but i
could `cabal install` it. try again later, please.
fix project name in .cabal.