check_by_ssh --help shows options which are not implemented

`check_by_ssh --help` displays 

```
 -w, --warning=DOUBLE
    Response time to result in warning status (seconds)
 -c, --critical=DOUBLE
    Response time to result in critical status (seconds)
```
but, actually neither `warning` nor `critical` is implemented.
Culprit is the line 457, which adds both in a generic way.