OSX results of XProtect hits
Updating the license comment to be the correct open source header

As per t5494224, all of the license headers in osquery needed to be updated
to reflect the correct open source header style.
Merge pull request #558 from facebook/license-header

Updating the license comment to be the correct open source header
Merge pull request #557 from theopolis/xprotect_results

OSX results of XProtect hits
Adding pcap event publisher
Adding basic network layer structs