Added South American region.

Also, added a function normaliseLocation tat removes the ambiguity in
the location constraint for EU (both "EU" and "eu-west-1" are valid
location constraints for this region).
Implemented GET Bucket location.
Use normaliseLocation.

This makes sure that one of the defined constants is returned for each region.
Merge pull request #124 from kantp/getbucketlocation

Implemented GET Bucket location