Added Wemo emulation for local Alexa control

With this release the gdhk proxy allows activation of a Belkin Wemo emulation layer, which allows for control of the Garage Door API with basic On/Off operations using Wemo clients (like Alexa).

The switch reports as "On" when the garage door is insecure (i.e. not closed), and "Off" when the door is fully closed. Triggering the switch to either state will change the target state of the door (asking Alexa to turn off the switch when the door is already closed will send the request to the demo protocol, but the garage door API will not change the state).

It is also possible to create routines so that saying, "Alexa, close the garage door" will attempt to turn the switch off, and vice-versa.

Docker image available for linux

From this point forward, all releases will also include a new docker image with the linux binary.
The docker image contains only the gdhk binary (which is the entrypoint). Start the docker image either with the gdhk flags as the command, or by configuring environment variables.

Initial WIP release

The gdhk HomeKit proxy can now be configured at startup, so users can run the proxy without having to modify values in the code.