depend on bson explicitely

package.json

@@ -4,6 +4,7 @@
   "description": "An online collaborative LaTeX editor",
   "dependencies": {
     "async": "^0.9.0",
+    "bson": "^1.0.4",
     "coffee-script": "^1.11.1",
     "east": "0.5.1",
     "east-mongo": "^0.1.2",