Display host address on row update

The host colume of the database table is calculated from
the ip address and / or hostname of the instance.

Currently this is calculated when the table is first
populated but not re-calculated  when a row is updated

Re-factor the code to use the same calculation to
determine the instance host information during row
update

Change-Id: Ic7b5e14918ea9d3196e0b591a8e57ccf6c0a71f1
Closes-Bug: #1336823
Merge "Display host address on row update"