fix(package): update ipfs-block to version 0.8.0

Author: greenkeeper[bot]

package.json

@@ -26,7 +26,7 @@
     "ethereumjs-account": "^2.0.4",
     "ethereumjs-block": "^2.0.0",
     "ethereumjs-tx": "^1.3.3",
-    "ipfs-block": "~0.7.1",
+    "ipfs-block": "~0.8.0",
     "merkle-patricia-tree": "^2.2.0",
     "multihashes": "~0.4.12",
     "multihashing-async": "~0.5.1",