pglookout: Create an alert file when we detect more than one master
pglookout: Create an alert file when we detect more than one master

Idea is to be able to easily create alerts if we have the abnormal
situation of having more than one master in the monitored cluster.

ohmu/pglookout,Ormod/pglookout,Ormod/pglookout,saaros/pglookout