Allow EVerest to function as a OpenADR VEN using our client

[pohlm01]

• Setup Everest Module based on examples
  • Write manifest definition (started)
  • Pass configuration (Endpoint, Auth, etc.) from Everest to client
• Poll VTN regularly and check upcoming limits
• Convert OpenADR Intervals into Everest Intervals (see EverestType)
• Build Everest configuration which uses our OpenADR node in a Software-in-the-loop setup
• Do a review with Qwello (?)