Modifications for SST Release

Added Jagan Jayaraj's change to HybridSystem.cpp to support running
HybridSim from different directories (uses the path of the hybridsim.ini
file to find the NVDIMM and DRAMSim ini files).

Added explicit typedef for uint.

Updated Makefile to use $(CXX) instead of g++ in all cases.

Added frontbuffer ini file for NVDIMM.