Added warning to readme.

ping #21

Author: Jim Schmid

README.md

@@ -1,5 +1,16 @@
+***
+
+**Warning**: There is currently a pretty serious issue reported. Until further notice,
+consider chunked uploads as *not-working*. It is highly recommended to switch from chunked
+uploads to non-chunked uploads until this issue is fixed again. You can find more
+information in ticket [#21](https://github.com/1up-lab/OneupUploaderBundle/issues/21).
+
+***
+
+
 OneupUploaderBundle
 ===================
+
 The OneupUploaderBundle for Symfony2 adds support for handling file uploads using one of the following Javascript libraries, or [your own implementation](https://github.com/1up-lab/OneupUploaderBundle/blob/master/Resources/doc/custom_uploader.md).
 
 * [FineUploader](http://fineuploader.com/)