Output hex strings.

vmtests.json

@@ -27,8 +27,7 @@
             "value" : "1000000000000000000"
         },
         "gas" : "9949",
-        "out" : [
-        ],
+        "out" : "0x",
         "post" : {
             "0f572e5295c57f15886f9b263e2f6d2d6c7b5ec6" : {
                 "balance" : "999999999999999926",
@@ -94,8 +93,7 @@
             "value" : "1000000000000000000"
         },
         "gas" : "9832",
-        "out" : [
-        ],
+        "out" : "0x",
         "post" : {
             "0f572e5295c57f15886f9b263e2f6d2d6c7b5ec6" : {
                 "balance" : "999999999999999959",
@@ -143,8 +141,7 @@
             "value" : "1000000000000000000"
         },
         "gas" : "9971",
-        "out" : [
-        ],
+        "out" : "0x",
         "post" : {
             "0f572e5295c57f15886f9b263e2f6d2d6c7b5ec6" : {
                 "balance" : "500000000000000000",
@@ -186,8 +183,7 @@
             "value" : "1000000000000000000"
         },
         "gas" : "9999",
-        "out" : [
-        ],
+        "out" : "0x",
         "post" : {
             "cd1722f3947def4cf144679da39c4c32bdc35681" : {
                 "balance" : "1000000000000000000",