Persistent primary node check for replicaset; python2 in shebang

85be2df49b: Integrated options to check for a persistent primary node in a replicaset by a defined node endpoint. The new primary node check does not need the special database 'nagios' any more. The original check's state switches back to OK when the primary changed after the second check cause the new primary node is written to the database after every check. The new check returns persistent notifications. It can be run against any replicaset member.
f8d76e90e8e: Replaced python interpreter in sheband with python2 cause check script does not run correctly under Python 3.