Refuse to update over USB because it's definitely broken right now

lib/controller.js

@@ -643,8 +643,8 @@ controller.update = function(opts) {
 
       // // If this Tessel isn't connected to the LAN
       if (!tessel.lanConnection || !tessel.lanConnection.authorized) {
-        // Warn the user that it's going to take a while
-        logs.warn('Warning: Authorized LAN connection not detected for this Tessel. For a faster update, cancel and connect Tessel to LAN with the `t2 wifi` command before update.');
+        // Reject because USB updates are broken...
+        return reject('No LAN connection found. USB-only updates do not work yet. Please ensure Tessel is connected to wifi and try again');
       }
 
       return updates.requestBuildList().then(function(builds) {