Simple mobility example.
Rename intfs, and add simple moveHost() function
Allow port selection in addIntf() and moveIntf()
Fix version check.
Pass rename correctly in moveSwitch()
wall clock time makes rt quota independent of nprocs
check if RT_GROUP_SCHED is enabled in kernel
Cluster edition prototype: remote nodes and links.

We add a new experimental feature to allow Mininet to run across
a cluster of machines. This is currently implemented via a set
mix-in classes that provide remote nodes that are implemented
via a connection to a remote shell, and remote links which are
tunnels across servers. In this preliminary implementation,
both control and data connections are made via ssh, but this
could change in the future.

A MininetCluster class is provided which allows existing code
to be used with minimal modification - all that is required is
to provide a list of servers to use. A customizable placement
algorithm may also be specified. An experimental CLI subclass
is also provided to make it easier to examine node placement;
status and links commands can also check whether nodes and
tunnels are still running.

Although this is an experimental feature, it does include a
--cluster option to make it convenient to start up a Mininet
simulation over a cluster, and a script to assist with setting
up the prerequisite authentication via ssh key pairs.

The cluster feature is preliminary and missing some obvious
important features, such as parallel startup and multiple tunnel
types, which we hope to add in the future.
if we do not receive a ping and cannot parse output, return errorTuple
adding sanity check for cluster edition
adding 'ports' command to cli
adding comments to CLI
add findUser() to clean up user identification
Merge pull request #359 from mininet/devel/cluster

Cluster Support Prototype
Merge pull request #376 from cdburkard/patches/pingOutput

if we do not receive a ping and cannot parse output, return errorTuple
adding example and test for intf.config
Merge pull request #374 from cdburkard/patches/rt

check if RT_GROUP_SCHED is enabled in kernel
Merge pull request #380 from cdburkard/devel/cli_comments

parse comments out of CLI
Merge pull request #381 from cdburkard/examples/interfaces

adding example and test for intf.config()
Merge pull request #379 from cdburkard/devel/show_ports

adding 'ports' command to cli