Catch correct ironic exception
Catch correct ironic exception

Catch exception from ironicclient instead of
fuel_health exceptions

Change-Id: I718638039b9ac2e0b93e93872085d3e083b3a6db
Closes-Bug: #1522740

eayunstack/fuel-ostf,eayunstack/fuel-ostf,stackforge/fuel-ostf,stackforge/fuel-ostf