Try using ntpd since ntpdate doesn't always work
ntpd doesn't take a server argument
update interface IP address with pexec so that backgrounded process output from the cli cannot interfere
fix a few small issues with walkthrough tests
Add 'use' test for using VM interactively
Wait for controller shutdown.

Unfortunately, this can slow things down a bit - perhaps
100-200 ms in the case of ovs-controller, but I am hoping that
it may help slightly with #399.
wait for sshd to start in example
Merge pull request #404 from cdburkard/patches/default_cli

use node.pexec() to update IP address of intf instead of node.cmd()
Minor fixes to wireshark test
Merge branch 'cdburkard-patches/test_walkthrough'
Add VM port forwarding option:  --forward tcp:2222:22
Merge pull request #407 from cdburkard/patches/baresshd_waitListening

wait for sshd to start in baresshd example