git-annex: 5.20140421

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.
darcs: 2.8.4
pandoc: 1.12.3
pandoc-citeproc: 0.3.0.1
shellcheck: 0.3.2
gsasl: add 1.8.0 bottle.
pandoc: add 1.12.3 bottle.
pandoc-citeproc: add 0.3.0.1 bottle.
shellcheck: add 0.3.2 bottle.
git-annex: add 5.20140421 bottle.
darcs: add 2.8.4 bottle.

Closes #27926.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>