DEPRECATED - Recommend using the scripts in https://github.com/dirkbeer/HotspotLatencyWebapp instead (even if you don't intend to create a web application)
Measure latency by running a simple bash script using cron in linux.
Plot using R.
Ideally installed on a machine not on the hotspots' network, like a Linode VPS.
