Revert "Move default Keystone API version to v3"

It seems like the fallout from this was not well sorted.
A lot of things aren't working, and there is still vestigial
v2 bits left behind.

This should have come with a much greater warning and some
spot checking of additional services working with this.

This reverts commit b162a1d58cdecfb32847b59bd341e06c26efb1ed.

Change-Id: Ia792b23119c00089542ba08879dca1c29dc80945
diff --git a/lib/heat b/lib/heat
index 3c3be79..df44b76 100644
--- a/lib/heat
+++ b/lib/heat
@@ -167,7 +167,7 @@
     iniset $HEAT_CONF clients_keystone auth_uri $KEYSTONE_AUTH_URI
 
     # ec2authtoken
-    iniset $HEAT_CONF ec2authtoken auth_uri $KEYSTONE_SERVICE_URI/v3
+    iniset $HEAT_CONF ec2authtoken auth_uri $KEYSTONE_SERVICE_URI/v2.0
 
     # OpenStack API
     iniset $HEAT_CONF heat_api bind_port $HEAT_API_PORT