Added 3 simple ggplot based examples.

I added three ggplot-based examples we can actually render with mpl support.

The plots are the following:

![ggplot](https://cloud.githubusercontent.com/assets/1640669/2605603/17833008-bb46-11e3-9a9a-3e7e73339154.png)

![time_ggplot](https://cloud.githubusercontent.com/assets/1640669/2605605/1b4b1386-bb46-11e3-9c88-4e54b7267dc8.png)

![stepggplot](https://cloud.githubusercontent.com/assets/1640669/2605606/1ea72e66-bb46-11e3-8999-f8ea0f2aa6b1.png)