Merge pull request #56 from bluescreen303/master

PostProcess.hs: relax trifecta's comonad dependency
PostProcess.hs: clean up code for git-annex so that the package can be built with doCheck=false
Add support for Apache license tag.

This change makes us dependent on Cabal 1.16.x or later.
PostProcess: fix for trifecta 1.1