#10 Use BINARY if capability available

[mistotebe]

Clients can try and upload binary data to the server if they think they
need to. imaplib2 should better mark its literals as binary per RFC 3516 if the
server advertises it to allow for that.

See https://github.com/OfflineIMAP/offlineimap/pull/274 for patch and rationale (Exchange can respond with binary data even if the client does not request it, offlineimap needs to be able to upload those messages to an IMAP4 compliant server in that case).

[Piers Lauder]

Thanks for the fix. Will incoporate shortly...

[Piers Lauder]

Suggested fix accepted and installed. Thanks!