Bullet point positioning fixes

The position of our signature Guardian bullet points used to be hugely different between platforms.

Because of the multiple ways browsers handle text rendering, It's unfortunately impossible to make bullet points look exactly the same across all browsers / OSs.

This is an attempt to normalise their appearance across most platforms.

Tested using a page containing all sorts of formats a list may be in: https://gist.github.com/kaelig/46ad81ac8218664d77c9

## Windows

![screen shot 2014-03-20 at 16 48 01](https://f.cloud.github.com/assets/85783/2474893/6d9f7d08-b050-11e3-968c-ec1507ee93e5.PNG)

![screen shot 2014-03-20 at 16 48 07](https://f.cloud.github.com/assets/85783/2474895/70c2c242-b050-11e3-9efb-37a3d99970df.PNG)


## Mac

![screen shot 2014-03-20 at 16 55 50](https://f.cloud.github.com/assets/85783/2474901/85bf19ac-b050-11e3-95c6-58fab64397dd.PNG)

![screen shot 2014-03-20 at 16 56 16](https://f.cloud.github.com/assets/85783/2474907/9223b69e-b050-11e3-97ae-ddfa5d9a484e.PNG)


## iOS
![screen shot 2014-03-20 at 16 48 37](https://f.cloud.github.com/assets/85783/2474890/64b87eb0-b050-11e3-88af-2be191409732.PNG)


![screen shot 2014-03-20 at 16 49 03](https://f.cloud.github.com/assets/85783/2474889/614d6ae2-b050-11e3-8b8b-4552c5343ef4.PNG)