0.4.0: MAJOR CHANGE TO NETWORK IDS AND NETWORK MEMBERSHIP (please upgrade!)

In keeping with the wild west alpha phase of this software, this version is
a major departure from 0.3.0 and an upgrade is required.

The protocol hasn't changed much, but the system of network membership, network
IDs, and network configuration bootstrapping has changed dramatically.

The mechanism for network autoconfiguration is now in-band, via the ZeroTier
protocol itself, rather than using an HTTP API. This simplifies the code and
allows us to use a consistent system of encryption and authentication.

To accomodate this change, network IDs now contain in their most significant
40 bits the ZeroTier address of a node responsible for overseeing the addressing
of participating network members. The remaining bits are free, so each network
controller (netconf node) can control up to 2^24 networks. The code for the
netconf service is in /netconf-service, but for ordinary users there's not much
need to look at it or use it. It's just there to be open source.

The system for network membership tracking is also revamped. For open networks
like Earth this doesn't matter, but for closed networks membership is now driven
by something called a membership certificate that is signed by the controlling
node in the network. There's still work to be done here, so private network
support isn't fully baked yet. But public open networks work fine.

Nodes still join "Earth" by default. The ID for Earth has changed from 1 to
6c92786fee000001 (hex). This means that old 0.3.0 clients and older will not
be able to communicate with 0.4.0 as their network IDs will not match.

The new certificate-based network membership system scales better than the old
HTTP API system and will support some pretty amazing features. Stay tuned!

For now just update and relaunch. You should get the same IPv4 address you
had before.

The second big change is zerotier-cli. Try running it as root (or after
copying the auth file to the path it tells you about when you first run it)
with 'help' as a command.