Add command to start script to run JobScheduler Universal Agent inside a Docker container

Desired Behaviour

• Add a new start argument "start_docker" to the agent startscript with the following effects
  • no user switching
  • JobSchedulerAgent is started as a background process but the startscript waits for the JobScheduler Agent process.
  • The startscript traps SIGINT, SIGHUP and SIGTERM to stop the JobScheduler Agent with its "stop" command ("{\$TYPE: Terminate, sigtermProcesses: false}")
  • log4j is configured to use the CONSOLE appender, not the FILE appender