AUTO-547: logging tenant/group/policy id when exec policy from webhook hash

removed existing cap_log since it is done already in with_transaction_id. Changed test accordingly

TODO: Add test for this binding
test for log binding

and using the log in errbacks too like @dreid suggested
Merge pull request #340 from rackerlabs/auto-547-webhook-log

AUTO-547: logging Ids when exec policy from webhook hash