destroy failed instances created by auto scaling

The ResourceFailure exception was silently eaten when raise_on_error
set to False. This patch handles the ResourceFailure exception locally
when raise_on_error set to False - called from ScalingPolicy alarm
(i.e. runtime adjustment). So users will not be charged for orphaned
instances. But they can still see what happened through event list.

Fixes bug #1192554

Change-Id: I01106d2e443dbc37af066b04ef7064bfa5656675
Merge "destroy failed instances created by auto scaling"