Make region specify-able in config

@karnowski - @ldenman and I were trying to provision a pairhost on the west coast and that stuff broke! Fog gem defaults to 'us-east-1' and my AWS services were 'us-west-2'... so the AMI instances were unavailable. So this makes the region specify-able in the config file.

:boom: Making the pairhost gem work on the West Coast!!! :boom:

Also, the Gem doesn't match master... which was confusing. What do we need to do to push another version update to the gem?