Modernize submitter integration

[leoschwarz]

• This implements a new submitter for our apps and will eventually obsolete the existing submitter code.
• The submitter has a config file which allows specfiying the Slurm parameter.
• Supported apps:
  • The initial version is implemented for app.yml apps, which have a directory on the worker node.
  • app.zip support will be added afterwards.
  • Legacy adds could be integrated as well with a "custom shell script" integration.