PEP8 cleanup
Fixed a couple things:
  * sniffer subsystem to allow parallel recording of pcaps
  * keyword_filtering nettest
  * improved some tests in test_oonibclient
Add support to the sniffer subsystem in the vagrant and requirements file
Added tests to the sniffer subsystem
PEP8 cleanup of utils
Added tests to generate_filename
Detect default interface with the one that is the default gateway.
Detect default interface with active probing.
Run the unittests as root so that the scapy tests get run by travis
Fix path of coverage so that running it in sudo does not trigger error.
Add service-identity to the requirements
Fix dummy config file of test_oonicli

* First install requirements.txt with pip
* Change default geoip datadir
Skip the oonicli tests if the user is not root.

(cherry picked from commit ef773f81d322bd733a9c8f3c5aac31a48c785a01)
Merge branch 'master' of https://github.com/TheTorProject/ooni-probe

Conflicts:
	ooni/reporter.py
	ooni/tests/test_oonicli.py
	ooni/utils/txscapy.py