whack: build and install binaries with a single command
=======================================================

Whack allows binaries such as nginx and node.js to be installed with a
single command. For instance, to install nginx 1.2.5 to
``~/apps/nginx``:

::

    whack install git+https://github.com/mwilliamson/whack-package-nginx.git \
        -pversion=1.2.5 ~/apps/nginx

Where possible, the build of each application will be relocatable. On
the first installation, the application is compiled and copied to the
target directory. On subsequent installations, a cached version of the
application is copied to the target directory.
