add datadog api key

Since this file will be the model for others to use for their vars
files, put in a placeholder DD api key, since it's required to be
*something* currently.
~/src group writeable, notifier pidfile workaround

celerybeat wants to write its pidfile to ~notifier/src.  Not sure why
the PID or CELERYD_PID_FILE environment variables don't correctly point
it to /var/run/... but in the meantime, this should get us by.