Add in-progress commit status change indicator

When deploying a changeset there is a time between when the ecs sends the command and juju ack's it. This time can be quite large on large deployments and on slow environments. This now changes the blue circle in the machine view to a yellow one until the juju ack.
Hmm, I see what you mean. Most of the code isn't looking at this value so there's a lot of existing code that would have to know to create models with the right value. Setting a value means this has a chance to be a lie. 

The more I think on it the more this might be right. I do think it's odd that the comments mention an assumed default if undefined. 

I'll make some other suggestions based on sticking with an undefined default.