Log warning if Compute cap property not provided
Log warning if Compute cap property not provided

TOSCA Compute capabilities OS and HOST properties are optional but if one or
more properites are not provided in template, can result into poor selection of
flavor or image. Log warning message for this case.

Change-Id: If45b06ac376042eba5177c074d38e8038e844c1a
Implements: blueprint handle-cli-user-input

openstack/heat-translator,openstack/heat-translator