Enhance bulk-o-matic application as load-test driver

Currently, most of stress/load testing is done via RESTCONF for openflow inventory model and flow-push.

1. this approach introduces variances caused by web-layer of ODL which can skew the observations.

2. Moreover, most of ODL apps using Openflow use binding-aware semantics and hence we would require a mechanism to drive load in binding-aware manner

So, in order to meet above, additional RPCs could be added to bulk-o-matic application with additional flexibility such as

1. ability to do BA DS based stressing for flow-provisioning
2. ability to do BA RPC based stressing fro low-provisioning
3. switch data-broker (eg. pinpong) on per test run basis
4. being able to specify test scenario parameters like flows per switch etc.