Location override feature

[nikhil153]

@Breakend Here is a PR for the issue we discussed (#57). It provides an option to specify region coordinates (longitude and latitude) for the cluster location. In unspecified, it defaults to the original ping the ipinfo.io approach.

I am not entirely clear on why location is queried by both the gather_initial_info() and _sample_and_log_power() functions, but regardless I have updated both of these to use specified longitude and latitude of the region.

Hope this helps!