Selection based sharing

Loads of cross-browser issues, so this is only active on non-touch devices.

![screen shot 2014-10-31 at 16 10 12](https://cloud.githubusercontent.com/assets/4549425/4863951/848d05fc-6118-11e4-9d79-e36aa18836e7.png)

You are probably using the same markup as other social icons are but do we need list for this? It almost feels like it can be just two links wrapped with the div.