Use saved file name of source and apk as default download file name

[derrell]

See also #114.

[derrell]

The HTTP header that needs to be sent looks something like this:

Content-Disposition: attachment; filename="your-name.here"

It looks like the static function aiagallery.dbif.Decoder64.getDecodedURL will need to retrieve the file name (from wherever it's stored), and add it to the returned map, so that the "getdata" portion of RpcServlet.js knows what to add to the header.

[derrell]

Consider naming file by project title instead of by original upload file name

[derrell]

Try this MIME type: application/vnd.android.package-archive