[zaphod-v0.3]: Command line support for start/stop/exec.

SYNOPSIS
[modified].gitignore: Ignore ssh.log
[modified]README: Specify dependency on paramiko and it version.
[modified]m42/test/test_zaphod.py: Cleanly close ssh regardless of errors.
[modified]m42/zaphod.py: Commented out debug prints.
[modified]zaphod: Command line support for start/stop/exec.

DETAILS
With this commit, the zaphod command line supports starting and
stopping a VM, as well as allowing execution arbitrary shell
commands. (Support for script execution is not directly supported.)