Add Stamen.TonerLite to hopglass-frontend

roles/hopglass-frontend/templates/hopglass-config.j2

@@ -19,6 +19,14 @@
             "config": {
                 "attribution": "Tiles © Esri — Source: Esri, i-cubed, USDA, USGS, AEX, GeoEye, Getmapping, Aerogrid, IGN, IGP, UPR-EGP, and the GIS User Community"
             }
+        },
+        {
+            "name": "Stamen (TonerLite)",
+            "url": "https://stamen-tiles-{s}.a.ssl.fastly.net/toner-lite/{z}/{x}/{y}.png",
+            "config": {
+                "maxZoom": 20,
+                "attribution": "Map tiles by <a href=\"http://stamen.com\">Stamen Design</a>, <a href=\"http://creativecommons.org/licenses/by/3.0\">CC BY 3.0</a> &mdash; Map data &copy; <a href=\"http://www.openstreetmap.org/copyright\">OpenStreetMap</a>"
+            }
         }
     ],
     "nodeInfos": [