Change constraints to build with current HP and Hackage

Without these contraint changes, I could not find any combination of packages that would build on my system using the current Haskell Platform (with versions pinned to that release set) and the current state of packages on Hackage.  With these changes it seems to build fine.  I am worried about why there was such a restrictive lower bound on `hashable`, though.  Is using 1.1.x going to even work?