Add "Locate Me" icon to map (in "Set Hint" view)

Added a "Locate Me" element to the map in the "Set Hint" view.
The icon is a placeholder, but by clicking the button the map pans
to the current position (retrieved via Cordova - not via Leaflet).
Change "Locate Me" icon on the map

Changed the "Locate Me" icon on the map (inside the "Set Hint" view).
The icon is still a placeholder but now it's a transparent PNG, which is
likely more similar to what the final icon will be.
Note that the custom "Locate Me" control is normally styled via CSS.