installing git-annex with cabal-install is quite long and requires to install
some heavy packages. It also has several external lib dependencies and needs a
few configuration flags to build so it is quite difficult to install too.
This formula should make it easy and quick to install with a bottle.

The huge number of haskell dependencies is built within the formula and statically
linked to git-annex. The haskell libraries built are discarded - cabal-install
should be used instead of this package in order to keep them.