Fix Minio SecurityContext Issues

Summary

On some cluster types minio is not deploying properly due to issues with (what appears to be) the security context. The symptoms are the minio instance pods fail to start up and a log error shows they don't have access to the proper file locations.

Several Big Bang users have run into this issue and had questions about it. One was able to resolve this by modifying the statefulset that runs minio with:

      securityContext: 
        runAsUser: 1000
        runAsGroup: 3000
        fsGroup: 2000     

The goal of this issue is to track down the bug and find a solution. Should be able to modify the PSP for Minio following this doc - https://github.com/minio/operator/blob/master/docs/pod-security-policy.md