genesis: adapt to geth 1.6

Change-Id: I9edde485f4b10b1d89cd8b068d9fc01a2d7a27d3

genesis.json

 {
-    "nonce": "0x0000000000000042",
-    "timestamp": "0x0",
-    "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
-    "extraData": "0x0",
-    "gasLimit": "0x8000000",
-    "difficulty": "0x400",
-    "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
-    "coinbase": "0x3333333333333333333333333333333333333333",
-    "alloc": {
-    }
-}
+    "config": {
+        "chainId": 4226,
+        "homesteadBlock": 0,
+        "eip155Block": 0,
+        "eip158Block": 0
+    },
+    "difficulty": "256",
+    "gasLimit": "134217728",
+    "alloc": {}
+}
\ No newline at end of file