Merge I/O fixes 2016/02/16 v1

# gpg: Signature made Tue 16 Feb 2016 15:42:29 GMT using RSA key ID 15104FDF
# gpg: Good signature from "Daniel P. Berrange <dan@berrange.com>"
# gpg:                 aka "Daniel P. Berrange <berrange@redhat.com>"

* remotes/berrange/tags/pull-io-next-2016-02-16-1:
  io: convert QIOChannelBuffer to use uint8_t instead of char
  io: introduce helper for creating channels from file descriptors
  io: improve docs for QIOChannelSocket async functions

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>