Show Journal Size In Navigation Bar

## Expected Behavior
Show in the Top Navigation in addition to *In/Out* of messages the size of the journal. Or have the option to customize this part of the UI to show either or.

## Current Behavior
Only the Messages coming in and going out to Elasticsearch are shown in the Top navigation as indicator about the System throughput.

## Possible Solution
Have the option as a user to customize that Metric part of the Top navigation with some pre defined values.

## Context
Currently you need to have an eye on some external monitoring dashboards to see if your setup buffers messages. Specially in bigger environments where you drop or clone messages the indicator for *IN/OUT* messages is not enough to have a first glance if everything work as expected.

Knowing the size of the Journal gives you more information if everything work as it should - at least in a well tuned environment.