fix(package): update react-dnd to version 8.0.0

Closes #149

Author: greenkeeper[bot]

package.json

@@ -67,7 +67,7 @@
     "qs": "^6.3.0",
     "react": "^15.3.2",
     "react-bootstrap": "^0.31.0",
-    "react-dnd": "^2.1.2",
+    "react-dnd": "^8.0.0",
     "react-dnd-html5-backend": "^2.1.2",
     "react-dom": "^15.3.2",
     "react-octicons": "0.0.5",