more on being smarter about waiting for the management daemon to start

cc333b39 worked for fresh systems, but if the system already had the daemon running the api.key file would already exist and the test would pass to early. Now removing the file first.

fixes #322

setup/management.sh

@@ -30,5 +30,8 @@ $(pwd)/management/backup.py
 EOF
 chmod +x /etc/cron.daily/mailinabox-backup
 
-# Start it.
+# Start it. Remove the api key file first so that start.sh
+# can wait for it to be created to know that the management
+# server is ready.
+rm -f /var/lib/mailinabox/api.key
 restart_service mailinabox