ENH FIX: Better realtime example + client waiting + realtime friendly plot_events

I tested the FieldTrip buffer in the actual MEG setup yesterday. The client would not wait for the server to start which was a bit annoying. So, I made the following changes. Also, the plot_events function is now realtime friendly so it can be used in an interactive loop.

![client_updates](https://cloud.githubusercontent.com/assets/3817535/3043844/d38b483c-e10a-11e3-8fa2-54ac137de75f.png)