Add support for {packet, N}

 - Add support for {packet, N} options
 - add ranch:set_options_defaults/2 which updates option proplist
   with default values.

{packet, N} option does not work when I'm testing, so I dig into codes, and found that {packet, N} option is blocked by ranch_tcp protocol, so I removed {packet, raw} enforcement and add it to default options.
Another fix introduces ranch:set_option_defaults/2, which removes multiple ranch:set_options_default/3 calls to insert default options.

Maybe It's better to create new protocol based on ranch_tcp if there is some reason not allowing {packet, N}. Please let me know in that case.