Fix css for #version

[mikepurvis]

The version paragraph of REP 127 is randomly centered and in a different font:

http://www.ros.org/reps/rep-0127.html#version

Given that there may be external links, I don't think the actual REP source should be changed, but this css contains the offending rule:

http://wiki.ros.org/moin_static197/rostheme/css/screen.css

I don't see where the rule is used on the actual ROS wiki, so it could either be dropped, or changed so that it's more specific, eg made #page #version rather than just #version.