Test on avclass_labeler.py

[CrimsonGlory]

Added one test to avclass_labeler.py.

To execute the test first we need to install pytest.
pip install pytest

and then pytest.

user@host:~/avclass$ pytest
=================================================== test session starts ===================================================
platform linux2 -- Python 2.7.15rc1, pytest-3.1.0, py-1.4.33, pluggy-0.4.0
rootdir: /var/www/html/final/avclass, inifile:
plugins: cov-2.5.1
collected 1 items 

tests/test_avclass_labeler.py .

================================================ 1 passed in 2.92 seconds =================================================