Correctly do swagger validation with experimental.

Before we tried both groups, first api then experimental. If
experimental failed, the error message would be discarded and the
message for api would be shown. This commit changes this behavior so
that we detect which api group we should be using and only show the
error for that group.

test/integration/framework/master_utils.go

@@ -140,16 +140,18 @@ func startMasterOrDie(masterConfig *master.Config) (*master.Master, *httptest.Se
 		}
 
 		masterConfig = &master.Config{
-			DatabaseStorage:    etcdStorage,
-			ExpDatabaseStorage: expEtcdStorage,
-			KubeletClient:      client.FakeKubeletClient{},
-			EnableLogsSupport:  false,
-			EnableProfiling:    true,
-			EnableUISupport:    false,
-			APIPrefix:          "/api",
-			APIGroupPrefix:     "/apis",
-			Authorizer:         apiserver.NewAlwaysAllowAuthorizer(),
-			AdmissionControl:   admit.NewAlwaysAdmit(),
+			DatabaseStorage:      etcdStorage,
+			ExpDatabaseStorage:   expEtcdStorage,
+			KubeletClient:        client.FakeKubeletClient{},
+			EnableExp:            true,
+			EnableLogsSupport:    false,
+			EnableProfiling:      true,
+			EnableSwaggerSupport: true,
+			EnableUISupport:      false,
+			APIPrefix:            "/api",
+			APIGroupPrefix:       "/apis",
+			Authorizer:           apiserver.NewAlwaysAllowAuthorizer(),
+			AdmissionControl:     admit.NewAlwaysAdmit(),
 		}
 	} else {
 		etcdStorage = masterConfig.DatabaseStorage