Wire up 'find my location' button

Use Leaflet Map.locate() api to grab user location and set marker
location.
Add location geosearch using L.GeoSearch plugin & OSM geocoding
Replace external location search with leaflet geosearch widget

Update geosearch widget from this fork:
https://github.com/gabrielflorit/L.GeoSearch
Remove current widgets and roll-your-own UI.
Replace 'find my location' button with Leaflet Locate control

Add L.Control.Locate widget
Remove 'Find My Location' button.