Upgrade node-buffer to v6.

Author: nsaunders

bower.json

@@ -24,7 +24,7 @@
     "purescript-http-methods": "^4.0.2",
     "purescript-indexed-monad": "^1.1.0",
     "purescript-media-types": "^4.0.1",
-    "purescript-node-buffer": "^5.0.0",
+    "purescript-node-buffer": "^6.0.0",
     "purescript-node-fs-aff": "^6.0.0",
     "purescript-node-http": "^5.0.1",
     "purescript-ordered-collections": "^1.6.1",