bump to 2.1.9 with windows threading fix

package.json

 {
     "name": "sqlite3",
     "description": "Asynchronous, non-blocking SQLite3 bindings",
-    "version": "2.1.8",
+    "version": "2.1.9",
     "homepage": "http://github.com/developmentseed/node-sqlite3",
     "author": {
         "name": "Development Seed",