Fix: add 'logrotate' tag to include statements

This tag is necessary for include directives in playbooks that
were recently modified to enable logfile rotation.  When the
'logrotate' tasks are picked by tag, the include statement
has to be run, too.
Improve robots.txt

* Parameterize sitemap url.
* Disallow robots outside of the production environment
Merge pull request #25 from dpla/add-sitemap-url

Parameterize sitemap URL
Add notifications to Munin and Slack notifier script