bump to v3.1.9 [publish binary]

package.json

 {
   "name": "sqlite3",
   "description": "Asynchronous, non-blocking SQLite3 bindings",
-  "version": "3.1.8",
+  "version": "3.1.9",
   "homepage": "http://github.com/mapbox/node-sqlite3",
   "author": {
     "name": "MapBox",