Functionality to support write of new files
Makefile - Added support for build test binary
dir_meta_ops.cpp - Added checks for file handle validity
file_handle.cpp - Modified for one to many mapping for filename -> file handle
file_handle.h - Modified for one to many mapping for filename -> file handle
file_meta_ops.cpp - Added checks for valid file handle
fs_options.cpp - moved globalFSOptions global variable definition to fs_options.cpp