[reSIProcate] Security.cxx updates

[Alan Hawrylyshen]

I checked in some minor changes that allow the SSL compatibility mode 
to be specified at the addTransportLevel().
This involved the creation of SecurityTypes.hxx -- which is quite 
skeletal right now.
This was to avoid circular dependencies with Security.hxx and not 
having to include it all over the place that might have to pass a 
SecurityTypes::SSLtype around.

Alan

a l a n a t j a s o m i d o t c o m