Add example httpd vhost config file

httpd.conf is only a partial configuration designed to be included in to
an existing vhost directive. This provides a (nearly) drop-in vhost
configuration for httpd.
fixup! 134d993 Use /srv/alaveteli instead of SITE_URL
fixup! 134d993 Remove PassengerGroup/User

Not available in Debian version of passenger
fixup! 134d993 Remove PassengerMinInstances

Not available in Debian version of passenger
Add link to Passenger performance tuning guide
fixup! 134d993 use apache2 rather than httpd for log dir

For dumb Debian convention
fixup! 134d993 Use easier to set up log dirs

Using alaveteli subdir means more setup; easier to just prefix the file name with alaveteli. Also use .log rather than _log to keep with original access.log and error.log convention.
Comment out forced redirect to HTTPS

Only need this if FORCE_SSL: true is set
Add example HTTPS vhost
Allow forced https rewrite to be configurable

Enable with:

    mkdir -p /etc/apache2/vhost.d/alaveteli
    cp /opt/alaveteli/config/httpd-force-ssl.conf-example \
      /etc/apache2/vhost.d/alaveteli/force-ssl.conf
fixup! ab1f215 Update SSL cert paths
fixup! ab1f215 fix typo
Remove unneeded httpd config directives

These are/were mySociety generic and not required for standalone use
Update httpd conf static asset location matching
Comment rarely-used httpd configuration

Unlikely that reusers will use this, but left for documentation purposes
fixup! 134d9934 fix PassengerAppRoot path
Group httpd  assets directives together
fixup! d7adeac
fixup! e8f30da
fixup! 2a0c4d7 add another passenger tuning guide