BugLink: http://bugs.launchpad.net/bugs/1470250

If a FREEZE operation takes too long, the driver may time out and move on
to another  operation. The daemon is unaware of this and attempts to
notify the driver that the FREEZE succeeded. This results in an error from
the driver and the daemon leaves the filesystem in frozen state.

Fix this by thawing the filesystem and continuing.
Signed-off-by: Alex Ng <alexng@messages.microsoft.com>
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Brad Figg <brad.figg@canonical.com>