fix travis

.travis.yml

@@ -1,5 +1,7 @@
 language: node_js
 node_js:
+  - "4"
+  - "6"
   - "8"
 sudo: required
 before_script:

package.json

@@ -28,7 +28,6 @@
   "dependencies": {
     "@mapbox/sexagesimal": "1.1.0",
     "@mapbox/togeojson": "0.16.0",
-    "colors": "^1.1.2",
     "diacritics": "1.3.0",
     "lodash-es": "4.17.4",
     "marked": "0.3.6",
@@ -40,6 +39,7 @@
     "@mapbox/maki": "^4.0.0",
     "brfs": "1.4.3",
     "chai": "^4.1.0",
+    "colors": "^1.1.2",
     "concat-files": "^0.1.1",
     "d3": "4.10.2",
     "ecstatic": "^3.0.0",
@@ -50,8 +50,8 @@
     "happen": "^0.3.1",
     "js-yaml": "^3.9.0",
     "json-stable-stringify": "^1.0.1",
-    "lodash": "^4.17.0",
     "jsonschema": "^1.1.0",
+    "lodash": "^4.17.0",
     "mapillary-js": "2.8.0",
     "minimist": "^1.2.0",
     "mocha": "^3.4.0",