Cleaned COBranch code

git-svn-id: svn://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@9943 7b3f36aa-e6db-49c1-8b4c-66eac1997e64
Removed unused -revisionWithUUID:

git-svn-id: svn://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@9944 7b3f36aa-e6db-49c1-8b4c-66eac1997e64