CP-5962: after rawhba installation the SR is not enabled by default

Even though it is packaged in the main ISO and installed
by default, this patch will prevent the SR type to
be usable unless the proper script is run

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>

GitHub: closes #192 xapi-project/sm
CA-139484: introduce TapdiskFailed exception type

Signed-off-by: Thanos Makatos <thanos.makatos@citrix.com>
Reviewed-by: Siddharth Vinothkumar <siddharth.vinothkumar@citrix.com>

GitHub: closes #193 on xapi-project/sm
CA-139739: encode NFS shares

Signed-off-by: Thanos Makatos <thanos.makatos@citrix.com>
Reviewed-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>

GitHub: closes #194 on xapi-project/sm