Fix check_has_entry for routing table

 - removed ^default from regex

On my debian box, having the command check for 
```shell
ip route | grep -E '^#{destination} |^default '
```
fails, whereas without the ^default, it works as expected.

Since a destination has to be supplied and since that destination can be 'default' as well, I do not see why this needs to be in here.

Cheers,
Sven