update .gitattributes to make sure vendored libraries are ignored
+bootstrap.css linguist-vendored
+bootstrap.js linguist-vendored
+fonts.css linguist-vendored
+jquery.js linguist-vendored
leaflet.js linguist-vendored
leaflet.editable.js linguist-vendored
leaflet.css linguist-vendored
material-icons.css linguist-vendored
+normalize.css linguist-vendored
