[cetic/nifi] Integrate with Nifi 2.0.0-M1

[CGeorgeLowe]

Upgrade to nifi 2.0.0-M1.

I recently wanted to use nifi 2.0.0 for better integration with AWS and timestream.

I've got it working with the lm chart with very little changes - specifically changing

nifi.flow.configuration.file=../data/flow.xml.gz -> nifi.flow.configuration.file=../data/flow.json.gz

hoping to push this up with a PR but I was wondering would we want to integrate the actual helm charts version to 2.0.0 also?

[banzo]

We could certainly start working on this.
Would you mind doing a PR?

Please Just keep the <20.0.0 config as a comment for backward compatibility.