Breaking change: Added ID() to Fingerprint interface. This allows us to assign
each fingerprint implementation a unique ID, identify which fingerprinters have
been run, and also self-identify in log messages.
- Added storage fingerprinter for Windows and *nix
- Added storage tests under storage_test.go
- Added test helper functions under fingerprint/fingerprint_test.go
- Added ID() to existing finterprinters and drivers
- Added Fingerprint.ID() to log messages via log.SetPrefix()
