Clojure: update CLASSPATH in the wrapper

Also add a test:
  brew test -v clojure

Formula/clojure.rb

@@ -6,26 +6,26 @@ class Clojure < Formula
   head 'https://github.com/clojure/clojure.git'
   homepage 'http://clojure.org/'
 
-  def jar
-    'clojure.jar'
-  end
+  def script; <<-EOS.undent
+    #!/bin/sh
+    # Clojure wrapper script.
+    # With no arguments runs Clojure's REPL.
 
-  def script
-<<-EOS
-#!/bin/sh
-# Runs clojure.
-# With no arguments, runs Clojure's REPL.
+    # Put the Clojure jar from the cellar and the current folder in the classpath.
+    CLOJURE=$CLASSPATH:#{prefix}/clojure.jar:${PWD}
 
-# resolve links - $0 may be a softlink
-CLOJURE=$CLASSPATH:$(brew --cellar)/#{name}/#{version}/#{jar}
-
-java -cp $CLOJURE clojure.main "$@"
-EOS
+    if [ "$#" -eq 0 ]; then
+        java -cp $CLOJURE clojure.main --repl
+    else
+        java -cp $CLOJURE clojure.main "$@"
+    fi
+    EOS
   end
 
   def install
     system "ant" if ARGV.build_head?
-    prefix.install jar
+    prefix.install 'clojure.jar'
+    (prefix+'classes').mkpath
     (bin+'clj').write script
   end
 
@@ -35,4 +35,8 @@ EOS
       http://trac.macports.org/browser/trunk/dports/lang/clojure/files/clj-rlwrap.sh?format=txt
     EOS
   end
+
+  def test
+    system "clj -e \"(println \\\"Hello World\\\")\""
+  end
 end