Filtering type extra-spec support to ZFSSA drivers

Filtering type extra-spec support to ZFSSA drivers

This change adds filtering type of extra specs to the ZFSSA drivers. It will
enable admins to create volume-types with the set of capabilities added by
this change.
Extra specs being added the ZFSSA iSCSI driver are: zfssa_poolprofile,
zfssa_volblocksize, zfssa_sparse, zfssa_compression, zfssa_logbias
Extra specs being added the ZFSSA NFS driver are: zfssa_poolprofile,
zfssa_sparse, zfssa_compression, zfssa_logbias, zfssa_encryption

Change-Id: I9167a50111f96921480dc30b350899035bf676bb
Implements: blueprint oracle-zfssa-extra-specs