fix(package): update d3 to version 5.10.1

Closes #45

Author: greenkeeper[bot]

package.json

@@ -20,7 +20,7 @@
     "connect-mongo": "^1.1.0",
     "cookie-parser": "^1.3.5",
     "csso": "^2.2.0",
-    "d3": "^4.1.1",
+    "d3": "^5.10.1",
     "errorhandler": "^1.4.2",
     "express": "^4.13.3",
     "express-flash": "^0.0.2",