NFS Provisioner: Changing provisioned volume mode to 0777

[hehesky]

Description of your changes:

Changing provisioned volume mode to 0777 by adding a chmod call after the dir is created

This is to allow non-root consumer pod to gain access to the volume. It is quite common now that pods are running as non-root user (sometimes even with restricted SCC). The consumer pod should be responsible for preparing the volume (i.e. changing the permission to proper values)

I also added on replace clause in go.mod otherwise it won't build (see #39).

Which issue is resolved by this Pull Request:
Resolves #22 and potentially a band-aid fix for #39

I've tested this change using a dev build running on Openshift 4.8 with portworx backing the server. With this change non-root pods are able to mount provisioned volume and gain access.

Checklist:

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• Reviewed the developer guide on Submitting a Pull Request
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