add GET /{tenant_id}/stacks/detail to Heat API

Enables the building of a useful dashboard interface for Heat stacks
without looping through stacks returned from "/{tenant_id}/stacks/"
to fetch the detailed data.

Fixes bug #1191117

Change-Id: I06b1100873de462c69302e43259df13104cad79f
Merge "add GET /{tenant_id}/stacks/detail to Heat API"