Add more tests to sickrage module

sickrage/media/GenericMedia.py

tests/sickrage_tests/__init__.py

tests/sickrage_tests/helper/__init__.py

tests/sickrage_tests/helper/common_tests.py

tests/sickrage_tests/media/__init__.py

tests/sickrage_tests/media/generic_media_tests.py

tests/sickrage_tests/media/show_banner_tests.py

tests/sickrage_tests/media/show_fan_art_tests.py

tests/sickrage_tests/media/show_network_logo_tests.py

tests/sickrage_tests/media/show_poster_tests.py

tests/sickrage_tests/show/__init__.py

tests/sickrage_tests/system/__init__.py