Add Travis CI integration
  - Add Gemfile for Bundler support
  - Fix dependencies
Convert to Rake ExtensionTask for native extension build
Add libpcap primitive support (create, set_rfmon, set_promisc, set_snaplen, set_timeout, activate).
Version bump
Merge pull request #16 from kevinmahaffey/master

Add Travis CI, update extension build, add more PCAP library support