- Provide an implementation for buildPool and deletePool operations
for the ZFS storage backend.
- Add VIR_STORAGE_POOL_SOURCE_DEVICE flag to ZFS pool poolOptions
as now we can specify devices to build pool from
- storagepool.rng: add an optional 'sourceinfodev' to 'sourcezfs' and
add an optional 'target' to 'poolzfs' entity
- Add a couple of tests to storagepoolxml2xmltest