Add automatic flake8 checking

.travis.yml

@@ -0,0 +1,8 @@
+sudo: false
+language: python
+matrix:
+  include:
+    - python: '3.6'
+      install:
+      - pip install flake8
+      script: flake8

setup.cfg

@@ -0,0 +1,21 @@
+[flake8]
+max-line-length = 110
+ignore = E133, E226, E228, N802, N803, N806, E266
+# TODO: remove E266 when Task documentation is converted to rst in DM-14207.
+exclude =
+    __init__.py,
+    diffimDetailLib.py,
+    diffimLib.py
+
+[tool:pytest]
+addopts = --flake8
+flake8-ignore = E133 E226 E228 N802 N803 N806
+    # TODO: remove E266 lines when Task documentation is converted to rst in DM-14207.
+    diaCatalogSourceSelector.py E266
+    dipoleMeasurement.py E266
+    imageDecorrelation.py E266
+    imageMapReduce.py E266
+    imagePsfMatch.py E266
+    modelPsfMatch.py E266
+    psfMatch.py E266
+    snapPsfMatch.py E266