Use the new AWS SDK

Outatime only needs S3, so this reduces the footprint of the gem.

Also, added frozen_string_literal as suggested in this article.

Improvements on how outatime fetches file revisions

• This release improves how outatime fetches file revisions. Now the download will start sooner, since it does not wait until all file revisions are fetched to start downloading the files.
• Use concurrent ruby to manage the fetcher thread pool.

Small improvements.

Merge pull request #3 from pressednet/updates_boone

Improve object version processing.

Initial Public Release

v0.2.0

Set license in gemspec.