Add support for route table routes to target virtual private gateways.
With @ethome, add filtering of instances by security group id
Merge pull request #275 from tsanders/vpn_gateway_routes

Add support for route table routes to target virtual private gateways.
Merge pull request #278 from cameron-r/master

Add filtering of instances by security group id
Add special S3 bucket create logic for us-east-1. Closes #273.
Add S3 location response. Closes #279.