Incorrect tunnel selection at OVS switch.

There are two vxlan tunnels which need to be created - one for ordinary traffic, other for SFC traffic. These two tunnels are of different types. Only one tunnel of it's type should be stored in HashMap located in SwitchManager. The same key though is used for both of these tunnel, so only one gets inserted. There is also a condition which allows tunnel to be put into that hashmap only if the map is empty. This causes ordinary traffic to be routed into a wrong tunnel.