load unsent events before handling utm and referrer

[djih]

There's a bug where during the initialization process, we load unsent events from localStorage into memory after we track the UTM params and referrer. What happens is that tracking the UTM params logs an event, and it will save the current in memory event queue to localStorage. However, since we haven't loaded the previous unsent events into memory yet, the queue will only contain the UTM param event, and it will overwrite the existing unsent events in localStorage. The solution is just to load the unsent events before handling the UTM params and referrer, or before any attempt to log an event really.