Bump NAN to 2.11.1

Author: cjbj

package.json

@@ -29,7 +29,7 @@
     "url": "git://github.com/oracle/node-oracledb.git"
   },
   "dependencies": {
-    "nan": "~2.10.0"
+    "nan": "~2.11.1"
   },
   "devDependencies": {
     "mocha": "^2.4.5",