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

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

# By Kevin Wolf (16) and Ian Main (2)
# Via Kevin Wolf
* kwolf/for-anthony:
  Add tests for sync modes 'TOP' and 'NONE'
  Implement sync modes for drive-backup.
  Implement qdict_flatten()
  blockdev: Split up 'cache' option
  blockdev: Rename 'readonly' option to 'read-only'
  qcow2: Use dashes instead of underscores in options
  blockdev: Rename I/O throttling options for QMP
  QemuOpts: Add qemu_opt_unset()
  block: Allow "driver" option on the top level
  qapi: Anonymous unions
  qapi.py: Maintain a list of union types
  qapi: Add consume argument to qmp_input_get_object()
  qapi: Flat unions with arbitrary discriminator
  qapi: Add visitor for implicit structs
  docs: Document QAPI union types
  qapi-visit.py: Implement 'base' for unions
  qapi-visit.py: Split off generate_visit_struct_fields()
  qapi-types.py: Implement 'base' for unions

Message-id: 1374870032-31672-1-git-send-email-kwolf@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>