Handle remote thrown NotFound RPC exceptions

This is a short-term fix for a regression caused by
If81b68717bd2f9d9be1291c07b18626493c9b5cc which results in undeletable
config and deployment resource if the underlying config or deployment
no longer exists.

Longer term there will be a ClientPlugin for making heat RPC calls
which wraps the remote exceptions and raises the original type.

The EngineClient methods local_error_name and ignore_error_named
will still be useful when this ClientPlugin exists, they just won't
be called directly from resources.

Change-Id: I8407e04c0404dd6560273d7d74744b5bb7774520
Merge "Handle remote thrown NotFound RPC exceptions"