Make aws region easy to add

I added (example values from https://github.com/aswoodward/fog/commit/fcf829839d897a81bbcbd36db02fe4f0c6ec74e5) 

Fog::AWS.additional_regions_info([{"messageSet" => [], "regionName" => "ap-southeast-2", "zoneName" => "ap-southeast-2a", "zoneState" => "available"},{"messageSet" => [], "regionName" => "ap-southeast-2", "zoneName" => "ap-southeast-2a", "zoneState" => "available"}])

Fog::AWS.set_additional_elb_hosted_zone_mapping({"ap-southeast-2" => "Z1WI8VXHPB1R38"})

this should cover the code changes in the pull request above except for lib/fog/aws/models/compute/server.rb  i was unsure what that did. 

Also I am looking for advice on how to test this. 

Also now that i looked at the code again perhaps a Fog::AWS.regions should handle all this logic in one place?

It looks like other services could use the same treatment. I see "add support for HP availability zone az-3.region-a.geo-1"  Maybe this concept can be further pulled out to support everyone.