Adding node label

[Ajay191191]

Adds a node label when selecting nodes for pods in case of the s3 source type. Deletes those nodes when the CR is deleted. This is a fix for issue #6.

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @Ajay191191. Thanks for your PR.

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[balajismaniam]

Fixes #6.