NetApp fix free space as zero during 1st vol stats update

NetApp clustered ontap drivers report space as zero
till first 60 seconds of driver start. This is causing
discomfort for some performance sensitive deployements.
This was due to async nature of the NetApp stats collection job.
Job is changed to sync at driver start to improve customer
experience.

Change-Id: I7d5cbf590897a0d328ece3a60516c92c0ad0ee7f
Closes-bug: #1253660
Pass the size when fetching image in xenapi driver

In commit 6e287c0f2bb7d4994d50f1763f412277e4dac6f7 the fetch_to_raw
method was changed to accept the volume size so it can fail when the
image doesn't fit in the destination volume. In this commit we also
updated all the volume drivers to pass the volume size to that method so
it could perform the check. The xenapi driver missed that change.

This commit updates the xenapi driver to pass the volume size when
fetching the image to enable the introduced check.

Change-Id: I89bc4b3b1c1e6b06f5c529166cf9ffa1fe600c96
Related-Bug: #1235358
Migrate volume should check para "host" in request

The server doesn't check whether the parameter "host" is in request
body. So the 500 error has been thrown.

We should catch the KeyError and transfer the KeyError to
400 (HTTPBadRequest) instead of 500.

Closes-Bug: #1253904
Change-Id: I3fb07113816a87f284b47e32bacd57f78a32676c
Fix docstring for _migrate_volume_completion

"Migrate a volume to the specified host." as the description of
_migrate_volume_completion func is incorrect.

Closes-Bug: #1253910
Change-Id: Ica944d9a7fa962ff56a9f0107ac1519623d2e551
Initialize and terminate connection raise 500 err

Initialize and terminate connection should check whether "connector" is
in request body. It throws 500 error if "connector" is not present. We
should catch the KeyError and transfer it to 400 (HTTPBadRequest)
instead of.

Closes-Bug: #1253944
Change-Id: If38419592701c8a14df52f94fd46ed0fc7a17e04
Merge "Migrate volume should check para "host" in request"
Merge "Initialize and terminate connection raise 500 err"
Merge "Fix docstring for _migrate_volume_completion"
Merge "NetApp fix free space as zero during 1st vol stats update"
Merge "Pass the size when fetching image in xenapi driver"