Move mapillary_sprite_source to devDependencies

package.json

@@ -34,7 +34,6 @@
     "@mapbox/togeojson": "0.16.0",
     "diacritics": "1.3.0",
     "lodash-es": "4.17.10",
-    "mapillary_sprite_source": "^1.4.0",
     "marked": "0.4.0",
     "node-diff3": "1.0.0",
     "osm-auth": "1.0.2",
@@ -63,6 +62,7 @@
     "json-stable-stringify": "^1.0.1",
     "jsonschema": "^1.1.0",
     "mapillary-js": "2.12.1",
+    "mapillary_sprite_source": "^1.4.0",
     "minimist": "^1.2.0",
     "mocha": "^5.0.0",
     "mocha-phantomjs-core": "^2.1.0",