Feature: Verify/Support AWS Data Pipeline error logs

**Background**

AWS Data Pipelines can log errors to an S3 bucket:

http://docs.aws.amazon.com/datapipeline/latest/DeveloperGuide/dp-error-logs.html

**Goal**

- Identify the log format
- Verify if StreamAlert's existing S3 support does support this use-case
- If yes, update the documentation and close this issue
- If not, put up a PR to add support (schema / parser) if feasible

Start with the AWS Data Pipeline error-log documentation linked in the issue and inspect StreamAlert's existing S3 support. Determine whether the log format is already supported; done means either documenting the verified support or proposing a PR for the schema/parser if feasible.

Written by the indexing model from the issue text.