Gyp support for node 0.8.16, necessary on OS X 10.8

Building with node-waf is no longer working on OS X 10.8 since it
enforces the i386 architecture. It needs to be x86_64 instead.

See also: https://github.com/joyent/node/issues/3633

I removed the wscript and added a simple binding.gyp

With the way node-gyp invokes the compile, I had an array
assignment error in line 67 on pcap_binding.cc which I
also corrected.

This version records http traffic on OS X 10.8.2, tested with mnot's
hdrgrab tool.