Scaling Scheduler for Job Service

Define and implement a solution for a Scaling Scheduler with Quartz, keeping the pluggability in mind.
The idea is to provide a backend based initially on PostgreSQL using Quartz in cluster mode, this can evolve and to provide different backends for Quartz (like infinispan), or in the future provide a new Scheduler implementation.

Besides a persistence abstraction for Job Service itself should be considered in this way to keep the same storage mechanism for Quartz and internally for Job Service.