upgrade nan to ^2.10

Author: trollkotze

package.json

@@ -17,7 +17,7 @@
     "bindings": "^1.3.0",
     "chai": "^4.1.2",
     "mocha": "^4.0.1",
-    "nan": "^2.7.0",
+    "nan": "^2.10.0",
     "napi": "0.0.0",
     "node-addon-api": "^1.0.0",
     "node-gyp": "3.6.2"