Issue #18 - Added limits to UAID and ChannelID

Also added preliminary support for update proxy support for sharding
Issue 16 - Added trapping for json parse errors

Also, moved genKey.go to sep. directory to get around mac go
complaints.
Issue #19 - added 200 response to ACK

While not defined by protocol, adding a 200 response to ACK so that the
server returns consistently.