Enable Startup of BPE without a running FHIR Server

[hhund]

Currently the BPE server tries to establish the websocket connection on startup. This results in a SocketTimeoutException if the FHIR server is not running. If the first connection is established, the websocket will automatically reconnect if a connection is lost.

The new Implementation should delay the connection attempt and retry (forever?) to establish a connection.

See also #105 for handling missed Task resources, while the BPE server was offline for a reboot for example.