Update README.md Sample app section

bottle-session needs to be installed for the sample app to work.

Author: j-e-d

README.md

@@ -198,6 +198,7 @@ This repository includes a one-file sample app that uses the bottle framework an
 authentication, subscriptions, and update processing. To try it out:
 
   * Download bottle if you don't already have it: pip install bottle
+  * Download bottle-session if you don't already have it: pip install bottle-session
   * Set your redirect URI to 'http://localhost:8515/oauth_callback' in your dev profile
   * Open up sample\_app.py, update it with your client\_id and secret, and set redirect URI to 'http://localhost:8515/oauth_callback'
   * Run the file; it will host a local server on port 8515.