Update config samples to show Identity v3 params

As Designate requests its service token using Identity v3, the
config.sample and some docs should reflect this. This patch updates
these files in order to conform to new v3 parameters.

Change-Id: I3205751f0c818f85ffe2fbb2468c6c48fd27eb91

doc/source/functional-tests.rst

@@ -45,7 +45,7 @@ The config file should look like the following:
     # Replace these with values that represent your identity configuration
     uri = http://localhost:5000/v2.0
     uri_v3 = http://localhost:5000/v3
-    auth_version = v2
+    auth_version = 3
     region = RegionOne
 
     username = demo

etc/designate/designate.conf.sample

@@ -160,11 +160,15 @@ debug = False
 [keystone_authtoken]
 #auth_host = 127.0.0.1
 #auth_port = 35357
+#auth_version = 3
 #auth_protocol = http
-#admin_tenant_name = service
-#admin_user = designate
-#admin_password = designate
+#project_name = service
+#username = designate
+#password = designate
+#project_domain_id = default
+#user_domain_id = default
 #memcached_servers = localhost:11211
+#auth_type = password
 
 #-----------------------
 # CORS Middleware