Create or update the template presentation demo using task `revealjs`.

def revealjs_template():
    '''Create or update the template presentation demo using task `revealjs`.
    '''
    from config import basedir, github_user, github_repo

    run(flo('rm -f {basedir}/index.html'))
    run(flo('rm -f {basedir}/slides.md'))
    run(flo('rm -f {basedir}/README.md'))
    run(flo('rm -rf {basedir}/img/'))

    title = 'reveal.js template'
    subtitle = '[reveal.js][3] presentation written ' \
               'in [markdown][4] set up with [fabric][5] & [fabsetup][6]'
    description = '''\
This presentation shows how to create a reveal.js presentation which will be
set up with the fabric task `setup.revealjs` of fabsetup.

Also, you can use this presentation source as a reveal.js template:
* Checkout this repo
* Then set the title in the `index.html` and edit the
  `slides.md`.'''

    execute(revealjs, basedir, title, subtitle, description,
            github_user, github_repo)

    # (README.md was removed, but not the github remote repo)
    print_msg('\n## Re-add github repo infos into README.md')
    basename = os.path.basename(basedir)
    _insert_repo_infos_into_readme(basedir, github_user=_lazy('github_user'),
                                   github_repo=_lazy('github_repo',
                                                     default=basename))

    print_msg('\n## Assure symbolic link not tracked by git exists\n')
    run(flo('ln -snf ../reveal.js  {basedir}/reveal.js/reveal.js'))