Add retrieval of approximate country coordinate and pan map to popup

[JeremyLoh]

Currently, only considering the countrycode (ISO 3166-1 Alpha-2 code). Not taking into consideration the state

• Show approximate location for country if the geo_lat and geo_long of the station information is not available (null)
• Update the station information during the call to get the random station. Use an existing Map consisting of countrycode => { longitude: number, latitude: number}

Countries with their (ISO 3166-1) Alpha-2 code, Alpha-3 code, UN M49, average latitude and longitude coordinates - https://gist.github.com/tadast/8827699

https://leafletjs.com/reference.html#map-event