Fix upload of big files

Upload of big files does not work anymore since seam 2 changes : the application seems to be stuck and jboss has to be restarted when using files with a size > 30Mb.

Now we're using the s:fileUpload tag and SeamMultipartFilter features to retrieve binary content, and convert it to blobs.
Configuration of maximum size is done in nuxeo.ear/OSGI-INF/templates/components.xml.
The filter configuration allows to decide whether files should be persisted or not, but anyway we persist it when converting it to a blob, so this configuration seems useless (and may even be a problem ?).
Conversion code is in nuxeo-platform-ui-web, FileUtils#createSerializableBlob and uses "StreamingBlob.createFromStream(file, mimeType).persist();"