Feature request: Try spot instance and fallback to on-demand

[mcassaniti]

The description should say it all. If the request to run a spot instance fails because of insufficient capacity it should fall back to requesting an on-demand instance. Something like market-type: try-spot.

[mcassaniti]

I created a gist that may help others if they run into issues with insufficient capacity in a region. See here.

[Preen]

Wow this is awesome. Should add/reference it to the readme!