Code review comment for ~asbalderson/juju-wait:machine-wait

The argument order in the wait function needs to be adjusted, so it is backwards compatible with callsites using positional parameters (of which there are probably none, as the only user of this as a library I'm aware of is using keyword parameters, but might as well avoid the possibility).

It would be better if the code used datetime instances for timestamps rather than floats, to match what is already being done elsewhere in the code. I'm not going to require this to be fixed though.