Publish network load metrics to cloudwatch, create dashboard

[nathanielrindlaub]

• pic count on camera (from mbase logs), so that we can monitor & visualize the image back log on each camera over time
• image transmitted event - could infer this from pic count delta from mbase logs, or from image directory watcher
• image taken event - this we'd have to get from delta from mbase logs, and that means storing last piccount event in state. Could use Low DB for that as we do for image Queue.
• latency (time each image spends siting on camera + transmission time) - have to get "Date/time original" from exif to calculate this

[nathanielrindlaub]

• CPU temp (from temp log or SixFab logs)
• RPi lost connections (from SixFab logs)

[nathanielrindlaub]

#27