Expose Cinder default_availability_zone

[woodardchristop]

Currently we only expose: cookbooks/cinder/attributes/default.rb:default["cinder"]["config"]["storage_availability_zone"] = "nova"

We need to add default_availability_zone for customers with multiple cinder AZ's

default availability zone to use when creating a new volume.

If this is not set then we use the value from the

storage_availability_zone option as the default

availability_zone for new volumes. (string value)

default_availability_zone=<None>

[woodardchristop]

Sorry copied comments and it is bold.