ruby: cleaned up ruby profilers

ruby: cleaned up ruby profilers
Cleaned up the ruby profilers by moving the memory controller profiling code
out of the main profiler object and into a separate object similar to the
current CacheProfiler.  Both the CacheProfiler and MemCntrlProfiler are
specific to a particular Ruby object, CacheMemory and MemoryControl
respectively.  Therefore, these profilers should not be SimObjects and
created by the python configuration system, but instead private objects.  This
simplifies the creation of these profilers.