Delay start of django app for mongodb

When running in daemon mode, the django app tries to connect to mongodb
before mongo is actually up and running.  This causes the start script
to end with a non-0 code and the container stops running.  To fix this,
delay the start of the django app by some arbitrary time to allow
mongodb to fully startup.

docker/files/docker-start.sh

@@ -3,6 +3,7 @@
 export DJANGO_SETTINGS_MODULE=formhub.preset.ehealth_docker
 
 sudo service mongodb start
+sleep 10
 sudo service postgresql start
 
 sudo -H -u postgres bash -c "createdb formhubdjangodb"