Merge remote-tracking branch 'kwolf/for-anthony' into staging

Merge remote-tracking branch 'kwolf/for-anthony' into staging

# By Kevin Wolf (16) and Stefan Hajnoczi (4)
# Via Kevin Wolf
* kwolf/for-anthony:
  qemu-iotests: add 053 unaligned compressed image size test
  block: Allow overriding backing.file.filename
  block: Remove filename parameter from .bdrv_file_open()
  vvfat: Use bdrv_open options instead of filename
  sheepdog: Use bdrv_open options instead of filename
  rbd: Use bdrv_open options instead of filename
  iscsi: Use bdrv_open options instead of filename
  gluster: Use bdrv_open options instead of filename
  curl: Use bdrv_open options instead of filename
  blkverify: Use bdrv_open options instead of filename
  blkdebug: Use bdrv_open options instead of filename
  raw-win32: Use bdrv_open options instead of filename
  raw-posix: Use bdrv_open options instead of filename
  block: Enable filename option
  block: Add driver-specific options for backing files
  block: Fail gracefully when using a format driver on protocol level
  qemu-iotests: Fix _filter_qemu
  qemu-img: do not zero-pad the compressed write buffer
  qcow: allow sub-cluster compressed write to last cluster
  qcow2: allow sub-cluster compressed write to last cluster

Message-id: 1366630294[email protected]
Signed-off-by: Anthony Liguori <[email protected]>