Add support for init containers

[CiucurDaniel]

This PR aims to add support for init containers. This will close the issue #33

Changes:

• Added new value extraInitContainers: [] in which the user can specify init containers to be added to the deployment.
• Added support for additional volumes and volume mounts with 2 new values: volumes: [] and volumeMounts: []
• Changed default value of externalTrafficPolicy from object {} to string. This was because helm template failed to render the chart in its curent state:

Error: values don't meet the specifications of the schema(s) in the following chart(s):
zipkin:
- service.externalTrafficPolicy: Invalid type. Expected: string, given: object

[codefromthecrypt]

if you don't mind fixing the sh: syntax error: unexpected "done" even if this PR didn't introduce it, appreciated.

[codefromthecrypt]

also if you don't mind rebasing. cheers

[CiucurDaniel]

hey @codefromthecrypt, could you have a brief look and merge if possible? I updated and it seems all checks passed this time.

[codefromthecrypt]

sorry was on holiday and missed the notification

[codefromthecrypt]

releasing as 0.4.0 thanks!

[CiucurDaniel]

no problem, hope you had a great holiday. Thank you for merging! 🚀