adding default overrideable AWS region

Allows fog connections to non US-EAST regions of AWS by
allowing this property to be overriden in stub files (meta.fog_config.region).

Without adding a region entry to the template, the manifest needs to modified after generation to add a regions for non us east regions. Just adding just a meta.fog_config.region value to the stub will not work.

Note: sorry for doubling up on pull requests - i hosed my for with a badly thought out force push.