6613 FIX launch docker fail with space named drive

Signed-off-by: Guillaume Dufour <guillaume.duff@gmail.com>
IMHO It would be simpler to just do:
```Go
i := 0
postSeparatorFields := strings.FieldsFunc(text[index+3:], func(r rune) bool {
  i++
  return i < 3 && unicode.IsSpace(r)
})
if len(postSeparatorFields) != 3 {
  p.Fstype = postSeparatorFields[0]
  p.Source = postSeparatorFields[1]
  p.VfsOpts = postSeparatorFields[2]
}
```