Since breaking up an S3 credentials file into Rails environments is already optional, use of Rails is easily made optional as well.
All tests pass, no tests added. Would a non-Rails appraisal be valuable?
Do you mind rebase your patch and send as proper pull request?
I wonder how it would be used without Rails framework though.
Make Storage::S3.parse_credentials use of Rails.env optional.
Closes #389, Closes #390