Switching Moodle main code repository to Git

Changes on moodle.org servers

1. stop automatic weekly tagging and daily version commits in CVS
2. take aways all CVS write access from main CVS moodle module at cvs.moodle.org (keep all contrib and lang modules unchanged)
3. sync git cvshead with CVS HEAD - override CVS checkout with files from current cvshead Git branch, wait for update and fix any potential problems
4. stop automatic cvs.moodle.org --> git.moodle.org sync
5. branch MOODLE_20_STABLE from CVS HEAD
6. tag 2.0 in CVS
7. create new master branch from cvshead in git.moodle.org
8. create new MOODLE_20_STABLE branch form master
9. tag 2.0 in Git repo
10. delete old cvshead branch in Git (the master is the correct name now)
11. set up git commit hooks that push mirrors to Github and Gitorious (all 4 branches, we need to set up keys for the moodlerobot)
12. set up git commit hook that triggers export to CVS commit mirror (all 4 branches)