sidekiq_alive 2.0.0

SidekiqAlive offers a solution to add liveness probe of a Sidekiq instance. How? A http server is started and on each requests validates that a liveness key is stored in Redis. If it is there means is working. A Sidekiq job is the responsable to storing this key. If Sidekiq stops processing jobs this key gets expired by Redis an consequently the http server will return a 500 error. This Job is responsible to requeue itself for the next liveness probe.