Fixed Lint issues

Author: smarek

library/src/main/java/com/loopj/android/http/AsyncHttpResponseHandler.java

@@ -425,7 +425,6 @@ protected void postRunnable(Runnable runnable) {
                 runnable.run();
             } else {
                 // Otherwise, run on provided handler
-                Utils.asserts(handler != null, "handler should not be null!");
                 handler.post(runnable);
             }
         }

library/src/main/java/com/loopj/android/http/JsonStreamerEntity.java

@@ -199,9 +199,9 @@ public void writeTo(final OutputStream out) throws IOException {
                         } else if (value instanceof JsonValueInterface) {
                             os.write(((JsonValueInterface) value).getEscapedJsonValue());
                         } else if (value instanceof org.json.JSONObject) {
-                            os.write(((org.json.JSONObject) value).toString().getBytes());
+                            os.write(value.toString().getBytes());
                         } else if (value instanceof org.json.JSONArray) {
-                            os.write(((org.json.JSONArray) value).toString().getBytes());
+                            os.write(value.toString().getBytes());
                         } else if (value instanceof Boolean) {
                             os.write((Boolean) value ? JSON_TRUE : JSON_FALSE);
                         } else if (value instanceof Long) {