Changed known compatible version. There's a lot of used standard libs

SattaiLanfear · SattaiLanfear · commit cd8a6d6b8f8a · 2012-03-29T00:24:06.000-04:00
that weren't available before 1.5 at the least.
diff --git a/README.markdown b/README.markdown
@@ -73,7 +73,7 @@ Minimum Required JDK
 
 `Java-WebSocket` is known to work with:
 
- * Java 1.4 (aka SE 6)
+ * Java 1.5 (aka SE 6)
  * Android 1.6 (API 4)
 
 Other JRE implementations may work as well, but haven't been tested.
