Send interface_ip in the node description

shade's interface_ip is the value in the server dict that we get from
nodepool that we want to use to connect to the test node, but it didn't
get fully plumbed through.

Change-Id: I636a62a4fc0a7b28fd0b7a6ea0345efd61eebefc
diff --git a/tests/base.py b/tests/base.py
index 4d358c9..a0a986a 100755
--- a/tests/base.py
+++ b/tests/base.py
@@ -996,6 +996,7 @@
                     provider='test-provider',
                     region='test-region',
                     az='test-az',
+                    interface_ip='127.0.0.1',
                     public_ipv4='127.0.0.1',
                     private_ipv4=None,
                     public_ipv6=None,