Print a warning message if no collector could be found to be configured, such as if you misspell a collector name.
Merge pull request #494 from craigcalef/notfound

Warn from diamond-setup if a collector was not found.
Ported docs on configuring Nagios from Metricinga to the NagiosPerfdataCollector.
Merge branch 'master' of https://github.com/craigcalef/Diamond