Create new prod build profile in Maven.

This prod build profile will produce a jar that is the same as the
normal build but with some metadata elided. To build and install to
your local repo, run:

mvn -Pprod,omit-extra-jars install -Dmaven.test.skip=true

The omit-extra-jars profile suppresses creation of the slim, sources,
and javadoc jars. The prod profile passes an extra flag to the ant task
that compiles Clojure code and suppresses source in the output jar.

To use this jar, specify an additional classifier=prod in your build
dependency.

Signed-off-by: Rich Hickey <richhickey@gmail.com>
more meta elision