Redshift watcher and auditor

*Adds a redshift watcher and auditor*
* The watcher simply calls to gather cluster descriptions
* The auditor simply looks for clusters outside of a VPC
* The UI is updated to have a redshift entry in the reports dropdown

*Minor Changes*
* Update .gitignore to hide a few dart related dirs not under source control.
* A bit of a refactor of ```security_monkey/__init__.py``` to DRY things.