Redshift watcher and auditor

**Add 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.