Version 0.7.1: Added authorization

New in this version:

• added authorization capabilities to the agent
• new configuration parameter application_api_keys contains a list of authorized API keys
  • if this parameters is any empty list, no authorization is needed
• new option parameter api_key has a reference to the used credential name
  • the reference looks as follows: {% credential credential_key_name %} (as stated by active workflow)
• check and receive queries need valid authorization now