Merge remote-tracking branch 'jtc/tags/block-pull-request' into staging

Merge remote-tracking branch 'jtc/tags/block-pull-request' into staging

# gpg: Signature made Fri 26 May 2017 08:22:27 PM BST
# gpg:                using RSA key 0xBDBE7B27C0DE3057
# gpg: Good signature from "Jeffrey Cody <jcody@redhat.com>"
# gpg:                 aka "Jeffrey Cody <jeff@codyprime.org>"
# gpg:                 aka "Jeffrey Cody <codyprime@gmail.com>"
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* jtc/tags/block-pull-request:
  block/gluster: glfs_lseek() workaround
  blockjob: use deferred_to_main_loop to indicate the coroutine has ended
  blockjob: reorganize block_job_completed_txn_abort
  blockjob: strengthen a bit test-blockjob-txn
  blockjob: group BlockJob transaction functions together
  blockjob: introduce block_job_cancel_async, check iostatus invariants
  blockjob: move iostatus reset inside block_job_user_resume
  blockjob: separate monitor and blockjob APIs
  blockjob: introduce block_job_pause/resume_all
  blockjob: introduce block_job_early_fail
  blockjob: remove iostatus_reset callback
  blockjob: remove unnecessary check

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>