Degree of collocation logger (or task share variance logger) was
only present in pcp.go. Copied that code into extrema and prog-extrema.
Also, exposed visibility of pcp/utils.go#cpuUtilsPerNode(...) and
pcp/utils.go#memUtilsPerNode(...) to public.
Taking pcp config file name (or path) from commandline.
In scheduler.go, also checking to see if provided pcp config file
exists. If not, then exitting.
