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)
Fix bug in filename generation
Throw an error if the measurement timeout is less than the bridge_reachability timeout
Fixed https://trac.torproject.org/projects/tor/ticket/11983 with the addition of some checks of incoherences in:
  * advanced:start_tor, tor:socks_port and tor:control_port
  * advanced:interface
Make optional the execution of check_incoherences from read_config.
Check empty section in config file to avoid AttributeErrors exceptions when parsing the file.
Fixed bug 11858: ooni might not look at requiresTor?
Make the filename generation unittests check for the correct filename