Clone only latest version of builpacks

You dont need the buildpack history, so save bandwith and space
Myself (alanjds) added to AUTHORS
AUTHORS got alphabetical again
include libmagiclwand-dev to get magick wand headers
use the libmagickcore-dev which is a dependeecy of magicwand
Merge pull request #20 from alanjds/patch-1

Clone buildpacks with --depth=1
Merge pull request #21 from nolman/master

update packages so that rmagick can install
Fixed build error 1 by adding short delay to build script
Removed newline from end of file
Merge pull request #23 from offerijns/master

Fixed build error 1 by adding short delay to build script
FIX bad place instanciation for builder, r buildpack
Merge remote-tracking branch 'upstream/master' into multi-buildpack