[BioRuby] added page to wiki describing how to use CVS branches

[Moses Hohman]

As promised a few weeks ago, I have finally completed a page describing 
how to use CVS branches (in preparation for the upcoming fork of 
BioRuby, allowing for the development of a Ruby 1.8-only version of 
BioRuby).

http://wiki.bioruby.org/English/?Using+CVS+branches

Please edit it as you see fit, or ask me to clarify anything that isn't 
clear (which is probably plenty).

Moses