Status bar notification update

First phase of a set of updates to the status bar notification.
This update expands the status bar notification with the telemetry data available on the action bar.
It also adds a `connect/disconnect` action button that allows toggle of the drone connection from the status bar.

![test](https://cloud.githubusercontent.com/assets/914968/3463539/4bd56bc8-023b-11e4-8085-9d1599b82f8e.png)

![test](https://cloud.githubusercontent.com/assets/914968/3463550/6cdeae42-023b-11e4-9513-7225b751a7af.png)

Maybe we should create a Time class inside Units.