Catching 500 from heat during stack-create

-fixing very weird behaviour, that returns 500
 from heat, for a while after a stack-create
 if we call resource-list
-this is some internal heat error trying to access
 not existent nova instance

Fixes-bug: #1301787
Change-Id: I9728affed707cc509b5ea466d87bf8835959e5bf
Merge "Catching 500 from heat during stack-create"