Meek/fix autoscaling regions

The issue I had with autoscale clusters and regions was that get_slice() had some ec2-specific code in it.  This fixes that.

I also upgrade to fog 1.20 and excon 0.31 as those work for me and I was having some errors without them.  It's your call on whether or not this is necessary.  I've got it in one of my other open pull requests for core ironfan as it is needed to support something else I did.