Tox support

- add code coverage
- add test support for 2.7
removing nose support, reverting back to py.test
Add test from wireshark website

- add traces from <http://wiki.wireshark.org/Development/PcapNg>
- test them by iterate over elements
Merge branch 'test-from-wireshark'
Merge pull request #3 from kartoch/master

Tox support