chore(package): update multihashes to version 0.4.0 (#122)

https://greenkeeper.io/

Author: greenkeeper[bot]

package.json

@@ -38,7 +38,7 @@
     "idb-pull-blob-store": "~0.5.1",
     "interface-pull-blob-store": "~0.6.0",
     "lodash": "^4.17.4",
-    "multihashes": "~0.3.3",
+    "multihashes": "~0.4.0",
     "ncp": "^2.0.0",
     "pre-commit": "^1.2.2",
     "rimraf": "^2.5.4"