src: bump NODE_MODULE_VERSION To 47

For Node.js v5.0.0, due to upgrade to V8 4.6 which has an incompatible
ABI

Author: rvagg

src/node_version.h

@@ -49,6 +49,6 @@
  * an API is broken in the C++ side, including in v8 or
  * other dependencies.
  */
-#define NODE_MODULE_VERSION 46 /* Node.js v4.0.0 */
+#define NODE_MODULE_VERSION 47 /* Node.js v5.0.0 */
 
 #endif  /* SRC_NODE_VERSION_H_ */