introducing OVSBridge
fallback to ovsb when no OF controller is unavailable
add cli usage information
support wireshark versions greater than 1.11
Merge pull request #410 from cdburkard/patches/tshark_walkthrough_1404

support wireshark versions greater than 1.11 in test_walkthrough
Merge pull request #411 from cdburkard/devel/cli_usage

add cli usage information
First crack at fixing multiple links

* Makes MultiGraph more like networkx.multigraph
* Adds converTo method
* Synchronizes node1 with xxx1 in link options
Allow natural sort to accept non-strings.
Allow Mininet() to accept multi-link topos w/correct params.
add example and test for multiple links
Minor fixes
Return (src, dst) in original order, and allow keys + data
merge HostWithPrivateDirs into Host
unmount private directories after use
ensure we retrieve a single PID when run on a cluster node
Try to prime the pump to avoid PACKET_INs during iperf test

Background: the reference controller is reactive and installs exact
match rules. By attempting to start a telnet session we make sure that
the ARP caches and TCP flow rules are set up (in one direction at
least) before the test starts.

This is intended to help with #413
fix silent failures when rt cannot be assigned
Remove unused edgeinfo
Fix edges() and add convertTo() to Topo() (with keys option)
Ignore link info when sorting links.