Listen to initial GBM_ALERT events

Currently we only listen to FLIGHT, GROUND, and FINAL notices (as well as subthreshold) from Fermi-GBM, which encompass all the alerts with higher confidence. However there are sometimes large gaps in time between these and the initial GBM_ALERT, meaning we could only learn of a coincidence hours after it occurs. An example of this: https://gcn.gsfc.nasa.gov/other/659183098.fermi

One possible solution is to begin to listen to these initial GBM_ALERT events as well, but automatically apply the 'NOT_GRB' label to prevent an automatic alert from being sent. This would still apply the 'EM_COINC' label and cause an impromptu meeting to evaluate the coincidence rather than potentially wait hours before knowing about it.