fix db opening error with absolute path on windows

fix SQLITE_CANTOPEN error when cached.Database is called with absolute path on windows
use path.resolve for getting absolute path

lib/sqlite3.js

@@ -26,9 +26,7 @@ sqlite3.cached = {
             return new Database(file, a, b);
         }
 
-        if (file[0] !== '/') {
-            file = path.join(process.cwd(), file);
-        }
+        file = path.resolve(file);
 
         if (!sqlite3.cached.objects[file]) {
             var db =sqlite3.cached.objects[file] = new Database(file, a, b);