Replace hook with heliopanel server.

[xaav]

The hook has caused many problems due to users being able to delete it. We can do better by implementing the following solution:

• Add python/cli/heliopanel_server.py to the scripts and code it to serve on a chosen port.
• Make HTTP JSON requests to the heliopanel_server.py.
• heliopanel_server.py executes the actions as the hook would.