Remove the /srv mount point for /dev/sdb

/dev/sdb will be /var/lib/nova/instances.  The /srv mount point
didn't work, and wasn't good for anything anyway.

Change-Id: I87f3708dd1a8ede7c6864ccf7466ef7bce6e11fa
Merge "Remove the /srv mount point for /dev/sdb" into production