fix: use anonymous credentials with goofys

[olevski]

I am trying to use datashim with a public bucket. And this should work (in theory).

After digging around I saw that goofys supports this. However contrary to this commit message it seems that to not use any credentials one can just omit the --profile argument and goofys will figure things out.

I tested this change out and things work now if I use empty strings for the credentials ("").

closes #131

For example this manifest will not work before this PR but works after this change:

apiVersion: com.ie.ibm.hpsys/v1alpha1
kind: Dataset
metadata:
  name: example-public-dataset
spec:
  local:
    type: "COS"
    accessKeyID: ""
    secretAccessKey: ""
    endpoint: "http://s3.amazonaws.com"
    bucket: "giab"
---
apiVersion: v1
kind: Pod
metadata:
  name: test-pod-tasko
spec:
  containers:
  - name: test
    image: ubuntu
    imagePullPolicy: IfNotPresent
    volumeMounts:
    - mountPath: /data
      name: s3bucket
    command: ["sleep", "99999999"]
  volumes:
  - name: s3bucket
    persistentVolumeClaim:
      claimName: example-public-dataset

[srikumar003]

Tested with minikube and merged. Thanks @olevski !