Allow downloads with long byte ranges

A client ran into a problem viewing large Videos in Nuxeo, root cause is that Integers have a max value of 2147483647 but the viewer can demand byte ranges which are larger than that. See https://github.com/nuxeo/nuxeo/blob/master/nuxeo-core/nuxeo-core-io/src/main/java/org/nuxeo/ecm/core/io/download/DownloadHelper.java#L76

DownloadHelper should use longs everywhere instead of parsing integers.