Remove redundant tunnel drop flows in table 110

ODL Version : distribution-karaf-0.5.2-Boron-SR2

Openstack Version : mitaka

Setup Details : 1 Control Node + 1 ODL node

Note: This problem only occurs when only the controller is stacked, and no compute nodes. The problem doesn't occur when controller and at least one compute node are used.

Steps to reproduce the issue:

1) Start Openstack and ODL
2) Create a network/subnet
3) Observe that tunnel flows are installed for the network/sunnet
4) Delete the above network
5) Problem: All tunnel flows in step 3) removed EXCEPT one flow in table 110.

cookie=0x0, duration=16.736s, table=110, n_packets=0, n_bytes=0, priority=8192,tun_id=0x449 actions=drop <=============== This flow should have been removed when the network is deleted