Sometimes logwatch logs will contain URLs and domain names that trip
on abuse lists.    Use a custom filter to remove these checks.

The directives provided by `mod_access_compat` are deprecated.  This
patch eliminates references to them.

The package solr installs and uses tomcat7.  Installing tomcat8 appears
to be a mistake for Debian Jessie.

Use newer native "write HTTP" plugin to send metrics to Librato, if configured.

Add a status vhost to apache, so that monit's http monitoring will work.
It doesn't particularly matter to the monit check what this vhost does
as long as it returns 200, but I thought it would be nice to use
apache's builtin status functionality.  Ideas cribbed from [1].  It
might also be possible to use monit's apache-status functionality to
alert on more sophisticated criteria, but this will do for now.

Open question: does collectd support apache-status? Might it also be
interested in this vhost?

Fixes #299.

[1] http://mmonit.com/wiki/Monit/MonitorApacheStatus

The tomcat6 user doesn't have the right privileges to run the
/etc/init.d/tomcat6 script.  Removing these lines allows monit to
restart tomcat if it stops for any reason, and makes the tomcat6 monit
config more consistent with other monit configs elsewhere.

This commit moves the monitoring role to the bottom of site.yml so that
it is executed after all other roles.

This is needed because the monitoring role conditionally installs Monit
configuration file based on whether some other packages have been
installed or not (such as ZNC).

This patch also adds a comment to the "monitoring" entry within the
"roles" list and a `roles/monitoring/README.md` file telling users why
the monitoring role has to come last.

Resolves #284

The other services monitored by the default monit task should always be present except in very custom setups.

Resolves #255.

This change set builds collectd from source and configures it in one of
the following ways:

- If Librato credentials are present, collectd will be configured to
send data points to Librato using the collectd-librato plugin.

- If no Librato credentials are present, collectd will be configured to
write RRD files locally (/opt/collectd/var/lib/collectd/rrd by default).