deploy using a key

conf.py

@@ -409,8 +409,8 @@ REDIRECTIONS = []
 # in a `nikola deploy` command as you like.
 DEPLOY_COMMANDS = {
     'default': [
-        "rsync -rav --delete --filter 'P /doc' output/* kwant@kwant-project.org:",
-        "rsync -av htaccess-apache kwant@kwant-project.org:/.htaccess",
+        "rsync -rav -e 'ssh -i deploy_key' --delete --filter 'P /doc' output/* kwant@kwant-project.org:",
+        "rsync -av -e 'ssh -i deploy_key' htaccess-apache kwant@kwant-project.org:/.htaccess",
     ]
 }