Make boot-stack pass reachable IP to new machines.

The default configuration of boot-stack will have the boot-stack VM at
192.0.2.1. Thus, we want Heat to pass that as the metadata service
address rather than 127.0.0.1.

Change-Id: I2dd0867490914d65b7325322ef80919c843603e0
Merge "Make boot-stack pass reachable IP to new machines."