Filetransfer using Streams (not Files) needs explicit flush()

I noticed that when using the OutputStream variant of sendFile(), one has to explicitely flush() the OutputStream before close() (fail to do that and you end up with a part of the file on the receiving side - probably zero bytes). This is a quite nasty behaviour that cost me quite a lot of time to debug. Please add a flush() in the close() routine of the respective OutputStream implementations (at least IBB in this case).

Thanks for noticing!

SMACK-231

Alex