Regions

I added the ability to specify which region a security group should be created in.

it affects this one https://github.com/sportngin/platform-firewall-manager/pull/16
I would actually suggest breaking this up a bit:

```ruby

def self.security_group_definition_files
  Dir["config/*.yml"].reject!{|file| file == "config/aws_keys.yml"}
end

def elf.config_security_groups
  security_group_definition_files.reject { |file| get_security_group_region(file) == region}
                                 .map { |file| File.basename(file,File.extname(file)) }
end
```