Customize CSV delimiter

# Expected Behavior

It should be possible to pass an option to customize the CSV delimiter. The option would be ignored when format is `json` or `pretty`.

Example:

```
# expect pipe character as delimiter
$ umapi user-create-bulk -i users.csv -D "|"
```

```
# output CSV with semicolon delimiter
$ umapi user-read-all -f csv -D ";"
```

# Actual Behavior

This behavior is not currently implemented.