Add UI option to change endpoint (Nominatim to Directions API)

[amyleew]

Add button / functionality to switch between router endpoints for better testing.

/cc @geohacker @TheMarex

[geohacker]

Yes!

cc @batpad

[gelinger777]

try

geocoder: Geocoder.nominatim({serviceUrl:'http://localhost:7070/'}),

in index.js at line 97 if somebody needs it