Belatedly added Ben H and Xavier to contributors.

They had a huge influence on the design of the caching model. The Shop,
which is probably my favourite bit of code in here, exists largely
thanks to them.

README.markdown

@@ -67,11 +67,13 @@ Other contributors include:
 [Jeremy Grant](http://github.com/jeremygrant),
 [Jon Guymon](http://github.com/gnarg),
 [James Healy](http://github.com/yob),
+[Ben Hoskings](http://github.com/benhoskings),
 [Evan David Light](http://github.com/elight),
 [Chris Lloyd](http://github.com/chrislloyd),
 [Adam Meehan](http://github.com/adzap),
 [Kyle Neath](http://github.com/kneath),
 [Lawrence Pit](http://github.com/lawrencepit),
+[Xavier Shay](http://github.com/xaviershay),
 [T.J. Sheehy](http://github.com/tjsheehy),
 [Roland Swingler](http://github.com/knaveofdiamonds),
 [Gareth Townsend](http://github.com/quamen),