Fix convertion problem with bytes in an unsigned byte. Patch provided by Laurent Querel

Author: jfarcand

src/main/java/com/ning/http/client/providers/jdk/JDKResponse.java

@@ -155,7 +155,7 @@ public int read() throws IOException {
                 active = parts[currentPos].getBodyPartBytes();
             }
 
-            return active[bytePos];
+            return active[bytePos] & 0xFF;
         }
     }