Add support for DLT_RAW. Now can read raw IP pcap files and the correct
IpV4Packet or IpV6Packet object is instantiated.
Make the unit tests not fail if the user does not have root privileges
Merge pull request #23 from pjsg/fix/unittest

Thank you. I merge these 2 commits. But I need to add some changes for DLT_RAW on OpenBSD and the properties-based packet factory.