Create initial commit to add support for axTLS using global TURBO_AXTLS flag.

Pushed SSL specific code out of iostream.lua into crypto.lua in order to impleme
nt native axTLS support.

The validate_hostname() functions has been written in lua when using TURBO_AXTLS and it uses a new added utility function util.strcasecmp() that performs a fast string case agnostic comparison.