Add sdist to build automation

.travis.yml

@@ -20,4 +20,5 @@ script:
   - "make html"
   - "cd .."
   - "python tests.py"
+  - "python setup.py sdist"
   - "python setup.py bdist_wheel"

build.sh

@@ -6,5 +6,7 @@ rstcheck README.rst
 cd docs && make html && cp -r _build/html/* ../../parsedmarc-docs/
 cd ..
 rm -rf dist/ build/
-python setup.py bdist_wheel
-
+flake8 parsedmarc.py
+flake8 tests.py
+python3 setup.py sdist
+python3 setup.py bdist_wheel