Serve IRC log files as MIME type text/plain.

* modules/meetbot/manifests/site.pp: Specify a nondefault vhost
template.

* modules/meetbot/templates/vhost.erb: New file, similar in content
to the default puppetlabs-apache vhost template but forcing MIME
type text/plain and a default encoding of UTF-8 for files ending in
a .log suffix.

Change-Id: Ief0253c2baac32b126472d0f97f0aa503adbbd7f
Merge "Serve IRC log files as MIME type text/plain."