Add support for IP-to-Lat/Long geocoding service

[jboarman]

Add support for ipstack.com's geocoding services so that a user can request records near an IP address input.

/nearest/{count}/{sourceType}/to/{location}[/within/{distance}/{units}]

Note that we will have to discern the data type of the location parameter as being either an IP address or Lat/Long or Postal Code.

Alternate IP-lookup services could be added later: https://resolve.rs/ip/geolocation.html (We can take requests or look at google search popularity or SEO link popularity checkers to assess top services to support)