OpenNMS Helm 4.0.2

This release fixes a bug with the Flow datasource and Grafana 6.4, as well as some other cosmetic changes to the Flow query interface.

• HELM-190: TypeError: Cannot read property 'toBits' of undefined
• HELM-192: Rendering Bug in Flow Query Builder
• HELM-193: Conversation Flow Histogram show "null" instead of Unknown/Other in legend