Feature: Support S3 Testing

[jacknagz]

Background

When testing the StreamAlert Lambda functions, it's necessary to create fake event records to send to the main handler for analysis. With AWS Kinesis and SNS this is straightforward, since the event contains the data to be analyzed/alerted on. However with s3 events, the data must be fetched out of band, which increases the complexity of testing.

Desired Outcome

The ability to test s3 based rules:

{
  "records": [
    {
      "data": "data,in,my,fake,object",
      "description": "Privileged wget commands to non Airbnb assets",
      "trigger": true,
      "source": "my.s3.bucket",
      "key": "my.fake.object",
      "service": "s3"
    }
  ]
}