Makes the Apache httpd collector report additional metrics about
workers by parsing the "Scoreboard".

In addition to reporting "IdleWorkers", the collector now reports
metrics for: 'StartingWorkers', 'ReadingWorkers', 'WritingWorkers',
'KeepaliveWorkers', 'DnsWorkers', 'ClosingWorkers', 'LoggingWorkers',
'FinishingWorkers', and 'CleanupWorkers'