Add leaflet

Fix build, make map component async and move computed to getter

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

js/src/main.ts

@@ -1,7 +1,6 @@
 // The Vue build version to load with the `import` command
 // (runtime-only or standalone) has been set in webpack.base.conf with an alias.
 import Vue from 'vue';
-// import * as VueGoogleMaps from 'vue2-google-maps';
 import VueSimpleMarkdown from 'vue-simple-markdown';
 import Buefy from 'buefy';
 import 'buefy/dist/buefy.css';