[lambda] Athena Partition Refresh SQS Refactor
[lambda] Athena Partition Refresh SQS Refactor

* Introduce polling of SQS for new S3 event notifications
* Filter the buckets which sent notifications, use this set in the hive table repair
* Split out the config and backoff methods into the global scope to be used by both Athena and SQS classes
* Delete messages on the SQS queue once processed
* Introduce a generic Exception class for failing the Lambda function and generating error metrics
* Revise docstring format for Google style compliance

airbnb/streamalert,airbnb/streamalert