Move away from inline switch on hard-coded region strings to looking up values in aws.Regions map. This approach is more sane and flexible since adding/removing regions will be done in one place. Also move away from weird dot notation to names Amazon itself uses like us-west-2. Note: this is a breaking change due to the region name convention change. Addresses issue #199
Merge pull request #201 from yourabi/master

Move away from inline switch on hard-coded region strings