UI improvements

Collapse the activity contexts by default and show a summary of the logs.
![elmlogger7](https://cloud.githubusercontent.com/assets/2818455/5291098/1974b9ae-7b03-11e4-8688-8718e723fed4.png)

The rule about animation timing is this: Lower it down to the lowest (i.e. quickest) value you think is reasonable. And then divide by 2 :smile: Snappy UI generally appears to be better UI.