boxplot

A PR to my own master for discussion.
It doesn't seem to be working.

```
import PyHighcharts
print PyHighcharts

from PyHighcharts import Highchart

chart = Highchart(renderTo='container')
chart.add_data_set([[1, 2, 3, 4, 5], [6, 7, 8, 9, 10]], type='boxplot')
chart.show()
```