Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2016-07-26' into staging

Block patches for 2.7.0-rc1

# gpg: Signature made Tue 26 Jul 2016 18:11:36 BST
# gpg:                using RSA key 0x3BB14202E838ACAD
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>"
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40
#      Subkey fingerprint: 58B3 81CE 2DC8 9CF9 9730  EE64 3BB1 4202 E838 ACAD

* remotes/maxreitz/tags/pull-block-2016-07-26:
  iotest: fix python based IO tests
  block: export LUKS specific data to qemu-img info
  crypto: add support for querying parameters for block encryption
  AioContext: correct comments
  qcow2: do not allocate extra memory

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