Quickstart example

[choldgraf]

There are many examples in the examples folder and in the readme, but I think it'd be most useful for new users to have a minimal quickstart example that shows off how to interact with the API on real data. It would be useful to have a jupyter notebook explaining how to go from raw numpy objects to an NWB format in the least number of steps possible. And then start building more complexity on top of that.

In addition, I think it'd be useful to have an example that pulls a public dataset from the web (e.g. an EEG dataset on a public site), loads its contents into memory, and then turns it into an NWB format.