Changed the IO, Disk and Network classes to not use a subprocess.
They now use psutil to get the metrics. Also, changed the linux
system metrics classes to subclass the AgentCheck class instead
of the old-style Check class. Added additional configuration
and changed monasca-setup to support that. Fixed some Python
2.6 incompatible string formatting issues.
Change-Id: I1f8b65bf48e48e2c598aa4950c194fbae2f9e337
Michael James Hoppal