Safari support

Off
![screen shot 2013-12-29 at 09 04 37](https://f.cloud.github.com/assets/49038/1819155/4750c580-7068-11e3-94d2-dbebdee400e0.png)

On
![screen shot 2013-12-29 at 09 04 42](https://f.cloud.github.com/assets/49038/1819154/45ce91e2-7068-11e3-84c4-962e205ff2d5.png)

Safari doesn't support colours, so I modified the logo to change the state of the circle to indicate on/off state.