Add first cut at Java interop

src/koans/java_interop.clj

@@ -0,0 +1,16 @@
+(meditations
+  "You may have done more with Java than you know"
+  (= __ (class "warfare")) ; hint: try typing (javadoc "warfare") in the REPL
+
+  "The dot signifies easy and direct Java interoperation"
+  (= __ (.toUpperCase "select * from"))
+
+  "But instance method calls are very different from normal functions"
+  (= ["SELECT" "FROM" "WHERE"] (map ___ ["select" "from" "where"]))
+
+  "Constructing might be harder than breaking"
+  (= 10 (let [latch (java.util.concurrent.CountDownLatch. __)]
+          (.getCount latch)))
+
+  "Static methods are slashing prices!"
+  (== __ (Math/pow 2 10)))