[graphite] add ability to pass env values to Graphite Pod

[NikolaeVarius]

What this PR does / why we need it:

This allows us to set environment variables for the underlying graphite Pod. The docker container that the graphite helm chart uses allows us to set configuration for the Graphite Web application via environment variables. However this chart does not currently allow us to set any Environment Variables, nor any other way of interacting with the underlying docker container

Upstream Docker Container: https://github.com/graphite-project/docker-graphite-statsd

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)

• fixes #

Special notes for your reviewer:

values.yaml

env:
    - name: example-name
      value: example-value

$ helm template ./
$
        env:
        - name: "STATSD_INTERFACE"
          value: udp
        - name: "GRAPHITE_TIME_ZONE"
          value: Etc/UTC
        - name: example-name
          value: "example-value"

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• [x ] DCO signed
• [x ] Chart Version bumped (if the pr is an update to an existing chart)
• [x ] Variables are documented in the README.md
• [x ] Title of the PR starts with chart name (e.g. [fluentd-elasticsearch])

[NikolaeVarius]

bumped to 0.7.0 and latest version of graphite container 1.1.7-6. Deploys fine on my k8s cluster and seems to be responding to the ENV variables when set as expected

Upon review, I guess for the purposes of the upgrade of this helm chart, its important to note that the graphite version update is needed in order to properly take advantage of the features documented for that container. I've confirmed that the documented features/bugfixes work with this upgrade