Add tolerations and local storage to the deployment

[VoroAndjaro]

The deployment has affinity in the form of nodeSelector but not tolerations for taints. This PR adds optional tolerations to the deployment resource.

Also, an optional persistent volume claim is created if enabled in the values; this allows the deployment to have a persistent storage to keep the emails, in case it is required.
The environment variables for the storage have to be set manually in the values like:

extraEnv:
  INBUCKET_STORAGE_TYPE: "file"
  INBUCKET_STORAGE_PARAMS: "path:/storage"

[cpanato]

thanks for this PR

[cpanato]

Error: UPGRADE FAILED: template: inbucket/templates/pvc.yaml:1:14: executing "inbucket/templates/pvc.yaml" at <.Values.persistence.enabled>: nil pointer evaluating interface {}.enabled