Rewrite rsync exclude rules in deploy task

Exclude `files/` directories and `settings.php` files from rsyncing.

deploy.py

@@ -128,7 +128,7 @@ def _rsync_platform(target, target_directory):
     """
     Helper function to rsync platform to server.
     """
-    local('rsync -a src/drupal/ {}@{}:{}'.format(target.get('user'), target.get('host'), target_directory))
+    local('rsync -a --exclude sites/*/settings.php --exclude sites/*/files src/drupal/ {}@{}:{}'.format(target.get('user'), target.get('host'), target_directory))
 
 
 def _aegir_provision_platform(platform, aegir_path, aegir_destsrv):