Enable Agent to run behind different Proxy URLs

Current Situation
If the Agent is configured to run behind a reverse proxy, the proxy must forward the path "/" to "/" on the agent. A new alias cannot be introduced.

Desired Behaviour

• An Agent should be able to run behind a different base URL of a reverse proxy
• A reverse proxie server can be used for multiple agents on one port for different URLs, e.g.:
  • https://proxy_host:10000/agent1 proxies http://agent_host:4445
  • https://proxy_host:10000/agent2 proxies http://agent_host:4446
  • https://proxy_host:10000/unit5/foo proxies http://agent_host:4447