Set Canonical

Hi,

Is it possible to set canonical for version pages of a rubygem? I think no one needs all the versions of a gem on Google search result.

![screen shot 2014-07-01 at 5 10 58 pm](https://cloud.githubusercontent.com/assets/1162120/3441721/b5c987aa-0108-11e4-8510-b585116c510e.png)