Make telemetry broadcast configurable

[evanlh]

Ideally we would only broadcast this if the channel has subscribers, and at the least make it configurable:

Removed from server/index.js:
var elapsed = Date.now() - modelStart;
var logObj = {timeStamp:Date.now(),session:req.sessionId,clientIp:req.clientIp,model:req.modelName,params:req.params,elapsed:elapsed};
ss.publish.channel('ss-angular.telemetry', 'modelTime', logObj);