EmsRefresh of Amazon Images for EBS only instances

https://bugzilla.redhat.com/show_bug.cgi?id=1139383

This is the first part of the ticket, it pertains to storing the
block_storage_only for flavors and root_device_type for images.
Once this data is filled in by the ems_refresh we will be able to
filter out invalid instance types during provisioning.
Sorry, I missed this.

So, this column refers to the type of instance the flavor can be applied to. As it stands, the column name appears to refer to the storage itself, as opposed to the instance or image. Maybe `block_storage_based_only?` would be better.