Update Wrapped instances for lens-4.0
Add Rewrapped instances for all Wrapped types
gitignore: cabal sandboxes
remove extraneous imports
travis: build with ghc-7.8.1-RC1, don't build with HEAD
travis: Allow build failure with 7.8.1-RC1

[ci skip]
Merge pull request #51 from diagrams/lens4

Update Wrapped instances for lens-4.0