We are a small, global nonprofit that has 100+ volunteers who work from different cities and countries. We have thousands of Word documents, Excel documents, and PDFs on Google Docs. We would like to hire someone to create a file-sharing service on Amazon S3/EC2. Ideally, we would like to have multiple folders and subfolders. Different sets of persons would have access to different sets of folders and subfolders (and different sets of documents). We do not want our files to be...