added dependency badge;

Hi, 

i added dependency badge for clj-time: it's shows a state of dependencies for the latest release and users can find a additional metadata about clj-time after clicking on badge. 

I think for you as maintainer of the library,  you'll like our [references](https://www.versioneye.com/clojure/clj-time:clj-time/references) feature, which shows all registered clojure libraries using clj-time.