correct api schema for instance patch

The api schema specification for the patch oepration is in error and
defined a parameter of "configuration_id" while the code (both in the
server and the client, and also all the tests) used "configuration".

A fix with fewer lines of code would have been to just embed the {
"type": "null" } into the definition of configuration_id but I am
going to be making additional changes to the way in which we signal
(through a put call) that we want to detach a configuration_id so I've
defined a null_configuration_id type which I can use there as
well.

To prevent this from reoccuring, additionalProperties has been set to
False.

Change-Id: Ic98050e487b0d8cd9a68e8c46169456a52e2b16c
Closes-Bug: #1460174

trove/common/apischema.py

@@ -197,9 +197,14 @@ users_list = {
     }
 }
 
+null_configuration_id = {
+    "type": "null"
+}
+
 configuration_id = {
     'oneOf': [
-        uuid
+        uuid,
+        null_configuration_id
     ]
 }
 
@@ -301,10 +306,12 @@ instance = {
             "instance": {
                 "type": "object",
                 "required": [],
+                "additionalProperties": False,
                 "properties": {
                     "slave_of": {},
+                    "replica_of": {},
                     "name": non_empty_string,
-                    "configuration_id": configuration_id,
+                    "configuration": configuration_id,
                 }
             }
         }

trove/instance/service.py

@@ -305,7 +305,9 @@ class InstanceController(wsgi.Controller):
         instance = models.Instance.load(context, id)
 
         args = {}
-        args['detach_replica'] = 'slave_of' in body['instance']
+        args['detach_replica'] = ('replica_of' in body['instance'] or
+                                  'slave_of' in body['instance'])
+
         if 'name' in body['instance']:
             args['name'] = body['instance']['name']
         if 'configuration' in body['instance']: