Avoid creating document with empty cmis:contentStreamFileName

Some CMIS clients such as Adobe Drive 2.1 create cmis:document with a content stream with the correct payload and mimetype info but leave the cmis:contentStreamFileName property empty (the filename of the file in the Adobe Drive is mapped to the cmis:name of the document only). In that case Nuxeo will create with a mimetype info but without a filename fields. This makes the user interface look inconsistent when browsing the content from the default JSF UI.

A propose workaround would be to automatically fill the cmis:contentStreamFileName from the info coming from the cmis:name (and potentially also from the cmis:contentStreamMimeType if the extension is missing so as to find a good looking filename consistent with the mimetype info).