Set region to unknown on startup

[madninja]

This sets the current/default region to a new “UNKNOWN” region to avoid invalid uplink packet reports, region parameters (and thus invalid downlinks) when the gateway can’t or has not received it’s asserted region from the config service yet.

It avoids sending packets with Unknown region information to the packet router since they can't really be responded to or handled.

A Maker can set the region to a known value at startup by using the GW_REGION environment variable. This may be useful for data only hotspots or to get faster initial uplinks at startup.

Fixes: #408

[madninja]

@ke6jjj only caveat to #408 is that the unknown region is printed as "UNKNOWN" instead of null. E.g.

{
  "region": "UNKNOWN"
}

That ok?

[ke6jjj]

@ke6jjj only caveat to #408 is that the unknown region is printed as "UNKNOWN" instead of null. E.g.

Well, unfortunately no. The idea is to return a proper null for the API in question. For JSON that really would be null. We're looking for something consistent that Makers can program to.

[madninja]

@ke6jjj only caveat to #408 is that the unknown region is printed as "UNKNOWN" instead of null. E.g.

Well, unfortunately no. The idea is to return a proper null for the API in question. For JSON that really would be null. We're looking for something consistent that Makers can program to.

Fixed