Merge pull request #135 from ethereumjs/update/ethjs-util

Update ethjs-util, require minimum 0.1.6

Author: holgerd77

package.json

@@ -105,7 +105,7 @@
   "dependencies": {
     "bn.js": "^4.11.0",
     "create-hash": "^1.1.2",
-    "ethjs-util": "^0.1.3",
+    "ethjs-util": "^0.1.6",
     "keccak": "^1.0.2",
     "rlp": "^2.0.0",
     "safe-buffer": "^5.1.1",