Geographic synonym lookup in searchLocations()

[gkarthik]

From @flaneuse : searchLocations would be MUCH more useful if there was a geographic synonym lookup function. If I try to lookup “USA” right now, I get no results. We could do this either by a gazetteer approach (store a list of synonyms for each location), or we could use a package that calls Google’s Geocode API to find the lat/lon of the location and let the user select what they mean.

We would need an api_key for google geocoding api.