massive refactoring against json config parsing

proxy/blackhole/config_json.go

@@ -0,0 +1,14 @@
+// +build json
+
+package blackhole
+
+import (
+	"github.com/v2ray/v2ray-core/proxy/internal/config"
+)
+
+func init() {
+	config.RegisterOutboundConnectionConfig("blackhole",
+		func(data []byte) (interface{}, error) {
+			return new(Config), nil
+		})
+}