Release 67: Memory Leak Fix

We use the common Java HTTP framework Jetty to serve the kPow UI.

In release 64 we advanced our Jetty dependency from 9.4.30 to 9.4.36. We believe this caused a slow memory leak due to a change in Jetty behaviour regarding websocket buffering and that change not being supported by the websocket library we use.

This change reverts Jetty to 9.4.30.

Release #67 is available on Dockerhub and to download as a JAR file.

docker pull operatr/kpow:67