How to install git annex assistant using cabal on Ubuntu LTS 12.4 2014-01-03

Git annex assistant is a magically (but not that easy to use) auto synchronisation solution of directories based on git.

Cabal is a the apt/pip/cpan/gems of haskell and git annex is written in haskell.

Since I've spent quite some time finding the correct way to do this and since anything with cabal is long, I'll share this with you to save you some time.