replaced newpath() with std::pair<std::string, std::string> split_subdir(const std::string&, const std::string&)
	for more read-ability and easier use;
added dive(const unsigned int&, const std::string&) which returns a path that represents a sub-path "\x\ levels"
	deep into the given path;
modified copy_directories_test_case to be more thorough;
added test cases for functions that I added;
UPDATED FILESYSTEM.CPP with the changes made during unit_testing;

Signed off by Jonathan <jonathancw@me.com>