Leiningen is for automating Clojure projects without setting your hair on
fire. Working on Clojure projects with tools designed for Java can be an
exercise in frustration. With Leiningen, you just write Clojure.

Leiningen bootstraps itself using the 'lein' shell script; there is no
separate 'install script'. It installs its dependencies upon the first run on
unix, so the first run will take longer.

Hence, this build script just installs the 'lein' shell script into /usr/bin/,
then you need to manually invoke 'lein self-install' as normal user, which
won't touch system directories but install some stuff into ~/.lein/.
