Modernize the C++ to accept variadic templates for signals with 6+ arguments

C++2003 didn't had variadic templates so different number of
arguments must have been already implemented in the templates
and since it's impossible to get the amount ot different methods
that paople write, a variadic template was neede.

now we can connect signal / slots with 6+ arguments.

Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>