src: bump NODE_MODULE_VERSION due to V8 API

V8 4.2 introduces some minor C++ API changes that make it necessary for
many native add-ons to recompile in order to be usable in v2.0.0+

PR-URL: nodejs#1532

Author: rvagg

src/node_version.h

@@ -45,6 +45,6 @@
  * an API is broken in the C++ side, including in v8 or
  * other dependencies.
  */
-#define NODE_MODULE_VERSION 43  /* io.js v1.1.0 */
+#define NODE_MODULE_VERSION 44  /* io.js v2.0.0 */
 
 #endif  /* SRC_NODE_VERSION_H_ */