Post memmon events to slacker

[Rotonen]

We would like to have an event feed of memmon events from the deployments where we use memmon.

[jone]

This would be awesome 👍
There is https://github.com/MTSolutions/superslacker, but this does not use the same API as our bin/slacker and I couldn't get it running.
It would be great to use bin/slacker so that we only have to configure it once. For doing that we'd have to write our own supervisor eventlistener.

@lukasgraf has proposed to create a better eventlistener, see https://github.com/4teamwork/improvement-proposals/issues/2