Refactor

[woutslabbinck]

Refactor actors:

• make it possible to configure the subscription client
  • Solid has now push (using webhook-notifications)
  • Every actor has a pull message client (through GeneralSubscriptionClient.ts)

Add demo class for the Philips Hue - Solid state use case through DemoSolidAgent.ts + updated README.md to add code to run it.

Remove old code that is not used anymore.