fix(package): update event-stream to version 4.0.1

Closes #79

Author: greenkeeper[bot]

package.json

@@ -15,7 +15,7 @@
     "async": "^2.1.5",
     "config": "~1.29.0",
     "ejs": "~2.5.6",
-    "event-stream": "~3.3.1",
+    "event-stream": "~4.0.1",
     "ogr2ogr": "~1.0.1",
     "request": "^2.51.0",
     "sphericalmercator": "~1.0.2"