added dev dependencies + pylintrc fix

pytest.ini

 [pytest]
-addopts = --pep8 --cov=./ -v
-pep8ignore = 
-    *.py E501
+addopts = --cov=./ -v

setup.py

 from setuptools import setup, find_packages
 
-VERSION = '0.2.2'
+VERSION = '0.2.3'
 
 setup(
     name='common_helper_files',
@@ -9,6 +9,10 @@ setup(
     install_requires=[
         'bitmath'
     ],
+    tests_require=[
+        'pytest',
+        'pytest-cov',
+    ],
     description='file operation helper functions',
     author='Fraunhofer FKIE',
     author_email='peter.weidenbach@fkie.fraunhofer.de',