Update OpenStreetMap provider in Basemaps.js

I would like to suggest using the now preferred https://tile.openstreetmap.org URL instead of the current one (`{s}.`), see

openstreetmap/operations#737

Also, changes attribution URL to HTTPS link (use direct links).
Furthermore, changes name to simply 'OpenStreetMap'. (use common name)

app/static/app/js/classes/Basemaps.js

@@ -20,10 +20,10 @@ export default [
   },
   {
     attribution:
-      '&copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a>',
+      '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a>',
     maxZoom: 21,
     minZoom: 0,
-    label: _("OSM Mapnik"),
-    url: "//{s}.tile.openstreetmap.org/{z}/{x}/{y}.png"
+    label: _("OpenStreetMap"),
+    url: "//tile.openstreetmap.org/{z}/{x}/{y}.png"
   }
 ];