Missing method argument in curl-sample to Open Sesam

Missing method argument in curl-sample to open a Sesam device.

Now:
```
curl https://parku.ch/v4/sesam/1234abcd \
    -u 098f6bcd4621d373cade4e832627b4f6:parku \
    -X PUT
```

Before:
```
curl https://parku.ch/v4/sesam/1234abcd \
    -u 098f6bcd4621d373cade4e832627b4f6:parku
```