Version 1.0.6

Changes in this release:

• New Degraded Performance Monitor system.
• Now including process CPU usage in metrics, for both stats API and log.
• Added support for preserve_host, defaults to true (i.e. reverse proxy).
• Redesigned queue system. No longer using async.queue() unless explicitly activated via use_queue param (default false).
• Added nice feature, so proxy process can renice itself on startup.
• Updated docs and unit tests.