ops-grant-perms fails if nfs datastore specified

Installing with the following options combined results in an error:
```
--ops-grant-perms
--volume-store=nfs://192.168.68.3/vic-volumes:nas'
```
Result:
```
Cannot init ops-user permissions, failure: Ops-User: RBACManager, Unable to find Datastores: datastore '192.168.68.3' not found. Exiting...
```

@lcastellano 