S3 Lambda Release Preparation

[danotorrey]

The following tasks need to be completed in order to release the initial graylog-lambda-s3 version:

• [x] Finish review/merge/release of GELF client fix. Drop copy of sources, pull in dependency.
• [x] Release Lambda function. Upload to Releases page.
• [x] Finish dashboard content.
• [x] Finish parameterization and stream association.
• [x] Open source the repo.
• [x] Test content pack.
• [x] Test Lambda function code
• [x] Finish Cloudflare documentation and README. Readme should have all config props and troubleshooting steps.
• [x] TLS notes