dnssd should not use plug as NonOlsrIf; it should only use one iface for this option: ap or secAp.

This should fix the dnssd bug we saw at AMC, which causes massive instability with wireless mesh links.

For testing, the nodes at LTS should be reflashed with this change, and tested in a configuration similar to AMC MagicNet, with both wired and wireless mesh links.
Merge pull request #17 from opentechinstitute/dnssd-fix

dnssd should not use plug as NonOlsrIf; it should only use one iface for...