[cetic/nifi] Request for a global.imageRegistry parameter

[yardenshoham]

Is your feature request related to a problem? Please describe.
I usually deploy using my own image registry, not docker hub. For that, I setup a global.imageRegistry parameter that all helm charts I deploy respect.

Describe the solution you'd like
I'd like the current image.repository parameter split into two. See this image from Bitnami's kafka helm chart:

[banzo]

Hi @yardenshoham can you provide a pull request that adds this option?

[yardenshoham]

@banzo I'll do it if you approve the addition of Bitnami's common helm chart as a dependency. It provides a great utility for the image field rendering logic.