Adds Support for the Heat EC2 Auth URI

Previously, the [ec2authtoken] auth_uri was missing from
data_mappings.  This caused the ec2 auth_uri within heat.conf
to be unconfigurable and would only default to the uri specified
in the Heat module.

Change-Id: I10d4bfd2eb8238345f4b713a17a2c713808d739c
Merge "Adds Support for the Heat EC2 Auth URI"