Downgrade hashable to 1.1.2.5

There are multiple packages that block hashable 1.2.x.x due to multiple confirmed segfaults when using this version. Check http://packdeps.haskellers.com/reverse/hashable - hashable 1.2 stops one from using: yesod and snap web frameworks, yi editor or reactive-banana FRP library. 1.1.2.5 works for every package requiring hashable.