Handle byte objects for python3.6+

[vin01]

Changes:

1. Handle byte objects for python3.6+

2. Upgrade vagrant config to use ubuntu 16.04 at least so that updated packages (six) are available. In 14.04 six version 1.5.2 is installed which leads to:

ImportError: cannot import name wraps

Also using upgraded pip to suppress warnings.

3. Fixed flake8 errors for escape sequences

./tests/ipvs_tests.py:521:51: W605 invalid escape sequence '\('
./tests/ipvs_tests.py:525:51: W605 invalid escape sequence '\('

Please review.