support wireshark versions greater than 1.11 in test_walkthrough

In wireshark 1.12, the -R option without the -2 option for two-pass analysis is deprecated. We need to use -Y for single pass analysis of traffic, because two-pass analysis is not supported for live captures.

We also do not install a custom wireshark plugin if the wireshark version is greater than 1.11. This means our protocol filter should be 'openflow_v1' instead of 'of'.