removing CVS in Handbook Updating and Upgrading chapter

[Warren Block]

CVS is going away soon, and we should not be advising people to start 
using them now.

This diff entirely removes cvsup, csup, and CVS references from the 
Updating and Upgrading chapter.  SVN URLs are also changed to the 
preferred form and links to the SVN mirrors are added.

Rendered: http://www.wonkity.com/~wblock/temp/cuttingedge-nocvs.html
     Diff: http://www.wonkity.com/~wblock/temp/cuttingedge-nocvs.diff