Add a clojars version badge to the README.md
Add a clojars version badge to the README.md

This simplifies and automates the display of the latest version. Its a shame
its not text so it can't be cut & paste, but its better then nothing and
maintained by clojars, so no reliance on some startup SaaS service that may
disappear tomorrow.

Signed-off-by: Ken Barber <470bc578162732ac7f9d387d34c4af4ca6e1b6f7@bob.sh>

fpringvaldsen/trapperkeeper-webserver-jetty9,camlow325/trapperkeeper-webserver-jetty9,nwolfe/trapperkeeper-webserver-jetty9,richardc/trapperkeeper-webserver-jetty9,fpringvaldsen/trapperkeeper-webserver-jetty9,nwolfe/trapperkeeper-webserver-jetty9,richardc/trapperkeeper-webserver-jetty9,rlinehan/trapperkeeper-webserver-jetty9,camlow325/trapperkeeper-webserver-jetty9,rlinehan/trapperkeeper-webserver-jetty9,puppetlabs/trapperkeeper-webserver-jetty9,puppetlabs/trapperkeeper-webserver-jetty9