Create Geocoder abstraction

routes/geocoders/Geocoder.ts

@@ -0,0 +1,11 @@
+import { GeoCoordinates } from "../../types";
+
+export abstract class Geocoder {
+	/**
+	 * Converts a location name to geographic coordinates.
+	 * @param location A location name.
+	 * @return A Promise that will be resolved with the GeoCoordinates of the specified location, or rejected with a
+	 * CodedError.
+	 */
+	public abstract geocodeLocation( location: string ): Promise<GeoCoordinates>;
+}