Allow getblock result to be string or BlockResult.

The getblock command has recently added a verbose flag which alters the
output.  The previous code added a new field "Hex" to the BlockResult, but
this is not consistent with the origin getblock RPC call which returns a
string when verbose is false and the BlockResult JSON object when it is
true.

This commit corrects that by first removing the Hex field from the
BlockResult and second allowing the result for getblock to be either form.

jsonapi.go

@@ -45,9 +45,10 @@ type InfoResult struct {
 	Errors          string  `json:"errors,omitempty"`
 }
 
-// BlockResult models the data from the getblock command.
+// BlockResult models the data from the getblock command when the verbose flag
+// is set.  When the verbose flag is not set, getblock return a hex-encoded
+// string.
 type BlockResult struct {
-	Hex           string        `json:"hex,omitempty"`
 	Hash          string        `json:"hash"`
 	Confirmations uint64        `json:"confirmations"`
 	Size          int           `json:"size"`
@@ -776,10 +777,21 @@ func ReadResultCmd(cmd string, message []byte) (Reply, error) {
 			result.Result = res
 		}
 	case "getblock":
-		var res BlockResult
-		err = json.Unmarshal(objmap["result"], &res)
-		if err == nil {
-			result.Result = res
+		// getblock can either return a JSON object or a hex-encoded
+		// string depending on the verbose flag.  Choose the right form
+		// accordingly.
+		if strings.Contains(string(objmap["result"]), "{") {
+			var res BlockResult
+			err = json.Unmarshal(objmap["result"], &res)
+			if err == nil {
+				result.Result = res
+			}
+		} else {
+			var res string
+			err = json.Unmarshal(objmap["result"], &res)
+			if err == nil {
+				result.Result = res
+			}
 		}
 	case "getrawtransaction":
 		var res TxRawResult