Fix stack_get_by_name does not list nested stack issue

The nested stack's owner_id is not None. When querying a result
filtered with owner_id=None, then nested stacks will not be
listed. The fix is to filter stack_get_by_name by stack name only and
add a new API stack_get_by_name_and_owner_id to filter via stack name
and owner id.

Change-Id: I659104f4936b567222108c211f77473ef35638c6
Closes-Bug: #1240892
Merge "Fix stack_get_by_name does not list nested stack issue"