Added region support for plumbum.

I made a first pass at adding region support to plumbum, trying to keep it as simple as possible. I added Auth section to example config files, because I found I needed it in the config when connecting to a different region other than us-east-1. The '{%-' changes in config.yaml.j2.example remove the extra line from the template generation. Finally, I added *.swp to .gitignore to remove vim swp backup files from the git status.