vault: fix formatting of IP addresses to support IPv6

At present an invalid URL to Vault will be produced in the event
of the IP address used being an IPv6 address.

zaza/openstack/charm_tests/vault/utils.py

@@ -27,6 +27,7 @@ import yaml
 import collections
 
 import zaza.model
+import zaza.openstack.charm_tests.test_utils as test_utils
 
 AUTH_FILE = "vault_tests.yaml"
 CharmVaultClient = collections.namedtuple(
@@ -101,7 +102,7 @@ def get_unit_api_url(ip):
     transport = 'http'
     if vault_config['ssl-cert']['value']:
         transport = 'https'
-    return '{}://{}:8200'.format(transport, ip)
+    return '{}://{}:8200'.format(transport, test_utils.format_addr(ip))
 
 
 def get_hvac_client(vault_url, cacert=None):