Add gluon-channel-survey package

This package gathers channel usage data once per day and distributes it via alfred. It is intended to evaluate real-world channel usage in order to maybe optimize the used channel (yes, that would involve a break with existing devices etc. etc.).

Each node reports the middle 4 bytes of each BSSID it sees per channel. The first and last byte is stripped to avoid counting VAPs multiple times. It sends these truncated BSSIDs instead of simple counters to de-duplicate the combined measurement of all nodes.

While scanning for networks, the normal wifi operation is impaired, thus it only scans once per day and uses a random time in the frame of one hour so that not the whole mesh goes down for a second at once. It scans between 21:00 and 22:00 because presumably most APs are running at that time, while they might be automatically or manually turned off at night or day.