[webhook] New, very simple binding for listening incomming http requests

[Piotr_Bojko]

Binding is delivered to Third party marketplace

Webhook HTTP binding

Webhook Binding This even lets you describe your own API/WebHooks for OpenHab. This is sometimes needed for external services or hardware that has limited ability to call http webhooks. Supported Things Only one thing is supported - webhook. This thing does not have any channels at first but let you add any number of it. Discovery Discovery is not supported Binding Configuration Main configuration of the created thing lies in its unique id. This is will be part of the url for a webhook endpoi…