fix(package): update cids to version 0.6.0

Author: greenkeeper[bot]

package.json

@@ -22,7 +22,7 @@
   "license": "MIT",
   "dependencies": {
     "async": "^2.6.0",
-    "cids": "~0.5.2",
+    "cids": "~0.6.0",
     "ethereumjs-account": "^2.0.4",
     "ethereumjs-block": "^2.1.0",
     "ethereumjs-tx": "^1.3.3",