fix: add missing multicodec dependency (#155)

* added missing multicodec dependency

* using ~ for multicodec dependency range because version < 1

Author: pgte

package.json

@@ -70,6 +70,7 @@
     "lodash.sortby": "^4.7.0",
     "lodash.uniqwith": "^4.5.0",
     "lodash.values": "^4.3.0",
+    "multicodec": "~0.2.5",
     "multihashing-async": "~0.4.7",
     "protons": "^1.0.0",
     "pull-defer": "^0.2.2",