Switch revision viewing to an action instead of a parameter

It seems some search engines are not taking into account matches in the parameters for the robots.txt exclude list. We need to exclude revision viewing from the search engine's spidered pages to reduce the load.

The solution is to replace

/xwiki/bin/view/Main/WebHome?rev=1.3

with

/xwiki/bin/rev/Main/WebHome/rev=1.3

Ludovic