Seems like File.copy doesn't do directories (as source, that is),
only files (as far as I can tell from reading the docs and trying
it in irb, punch me if I'm wrong). It only creates a zero byte file
in the target directory on my system.
Replaced File.copy with a system call to 'cp -R ...' to do the job.
Seems like FileUtils could have done it just as well (with cp_r),
but I figured making a system call was better than introducing a
new dependency.
Added Rakefile that does install and uninstall.
Also providded are sub-tasks that do things like build GitX, copy it to
~/Applications/ or /Applications/, cleaning the build and removing GitX.app
Signed-off-by: Pieter de Bie <pdebie@ai.rug.nl>