Fix log message for scp, off-by-one-error...
Update EC2 AMIs
Factor ssh master stopping code into a separate public method.

Will be used in a future fix.
Kill the ssh master connection when stopping machines.
Doh
MachineState: the master control socket is needed in multiple methods
tests.py: Don't include the coverage-tests.py file I'm about to add
tests.py: Only run if called directly
Add coverage tests
Add html output generation to coverage run
Add nose/coverage to buildInputs for convenience (running with --run-env)