SEBA-909 store flows and implement GetFlow API

Change-Id: If2c214f8be5808ef89e0521f75d03da49153dc2a
diff --git a/api/bbsim/bbsim.yaml b/api/bbsim/bbsim.yaml
index 1d69552..0c23240 100644
--- a/api/bbsim/bbsim.yaml
+++ b/api/bbsim/bbsim.yaml
@@ -31,6 +31,10 @@
     delete: "/v1/olt/onus/{SerialNumber}"
   - selector: bbsim.BBSim.PoweronONU
     post: "/v1/olt/onus/{SerialNumber}"
+  - selector: bbsim.BBSim.GetFlows
+    get: "/v1/olt/onus/{SerialNumber}/flows"
+    additional_bindings:
+      - get: "/v1/olt/flows"
   - selector: bbsim.BBSim.SetOnuAlarmIndication
     post: "/v1/olt/onus/{SerialNumber}/alarms/{AlarmType}/{Status}"
   - selector: bbsim.BBSim.GetOnuTrafficSchedulers