Added pycodestyle checks

Changed .travis.yml to download pep8 module
Added pycodestyle conformance checks to be run by nosetests

.gitlab-ci.yml

@@ -3,7 +3,7 @@ tests-stretch:
   image: debian:stretch
   script:
     - apt-get update
-    - apt-get install -y python3 python3-apt python3-yaml python3-pytest git rsync libclass-accessor-perl libdpkg-perl libyaml-syck-perl
+    - apt-get install -y python3 python3-apt python3-yaml python3-pep8 python3-pytest git rsync libclass-accessor-perl libdpkg-perl libyaml-syck-perl
     - ci/gitlab-ci-runner
 
 tests-sid:
@@ -11,7 +11,7 @@ tests-sid:
   image: debian:sid
   script:
     - apt-get update
-    - apt-get install -y python3 python3-apt python3-yaml python3-coverage python3-pytest python3-pytest-cov git rsync libclass-accessor-perl libdpkg-perl libyaml-syck-perl
+    - apt-get install -y python3 python3-apt python3-yaml python3-coverage python3-pep8 python3-pytest python3-pytest-cov git rsync libclass-accessor-perl libdpkg-perl libyaml-syck-perl
     - ci/gitlab-ci-runner --with-coverage
   artifacts:
     paths:

Dockerfile

@@ -1,4 +1,4 @@
 FROM debian:stable
 WORKDIR /britney
 ADD . /britney
-RUN apt-get update && apt-get install --no-install-recommends --assume-yes python3 python3-apt python3-yaml python3-coverage python3-nose rsync libclass-accessor-perl libdpkg-perl libyaml-syck-perl curl
+RUN apt-get update && apt-get install --no-install-recommends --assume-yes python3 python3-apt python3-yaml python3-coverage python3-nose python3-pep8 rsync libclass-accessor-perl libdpkg-perl libyaml-syck-perl curl

tests/test_pycodestyle.py

@@ -0,0 +1,12 @@
+import unittest
+import pep8
+
+
+class TestCodeFormat(unittest.TestCase):
+
+    def test_conformance(self):
+        """Test that we conform to PEP-8."""
+        style = pep8.StyleGuide()
+        result = style.check_files('.')
+        self.assertEqual(result.total_errors, 0,
+                         "Found code style errors (and warnings).")