Added an XML block to support Clojure files. Adapted from http://softnoise.wordpress.com/2010/03/15/clojure-source-files-in-quick-look-on-macosx/
Made a copy of the clojure.lang file and called it clj.lang so the plugin will highlight Clojure files that have .clj as the extension.
Added the .clojure file extension as a <string> to the .plist file so that Clojure source code files with .clojure as the extension get highlighted too.
Updated README files.
Merge pull request #1 from nickchappell/feature/add_Clojure_support

Feature: Add Clojure support