Make IEC/SI map global so it can be used externally
Be more consistent and specify the zvol size in IEC

While I'm here accept spaces.

Ticket:	#4857
Show zvols size using IEC suffix for consistency

Ticket:	#4857
Fix SI suffix for kilobyte
Correct debug entry.

Ticket: #4863
Delay updates and deletes to make the process appear more like atomic.

Ticket: #4871
Merge remote-tracking branch 'origin/master' into poudriere