Blockstorage updates

* Added Blockstorage Datasets
* Added per-volume-type min and max size configurability.
* Added behavior method for getting min and max size of
  configured volume types
* Added 'default' min and max volume type properties to the
  volumes_api config, which deprecate the older min and max
  volume_size properties.
* Added volume_type_properties property in volumes_api config
* Added Image, Flavor, and Volume Type filters and filter mode
  options to the volumes_api config.
* Added configuration option for toggling cross-type snapshot
  restores (since this will soon be configurable in cinder)

Change-Id: I8a4ba2de4dda66c61abf14938dfd14635ff68456
Merge "Blockstorage updates"