Change gitignore to ignore .DS_Store.
Get ride of v8 clone.

It segfaults.
Useful to print out the exit code.
Fix a bunch of typos.
Implement promiscuous mode.

Looks like Linux only allows the raw sockets to send with a different
mac addr in promiscuous mode.  Go ahead and set that up before opening.
Show the length of the packet.
Checksumming is broken.

Looks like hardware will compute the ethernet header for you.