add flake8 config and enable in travis

.travis.yml

@@ -50,6 +50,7 @@ before_script:
 script:
   - on_host do_on linux bitcoind --help | head -1
   - on_host do_on linux ./test/run_tests.sh
+  - on_host do_on linux flake8 jmbase jmbitcoin jmclient jmdaemon scripts test
   - on_docker ./test/Dockerfiles/build_docker.sh
 after_success:
   - on_docker echo "Success !"

requirements-dev.txt

@@ -6,4 +6,4 @@ pytest
 pytest-cov
 python-coveralls
 mock
-
+flake8

setup.cfg

@@ -1,3 +1,24 @@
 # content of pytest.ini
 [tool:pytest]
 testpaths = jmbitcoin jmclient jmbase jmdaemon test
+
+[flake8]
+exclude =
+    # defaults
+    .svn,CVS,.bzr,.hg,.git,__pycache__,.tox,
+    # lots of "unused imports"
+    __init__.py,
+    # unmaintained
+    jmclient/jmclient/slowaes.py
+
+# default value, keep?
+max-line-length = 79
+
+statistics = True
+max-complexity = 15
+
+# should be extended once existing issues are fixed
+select = F,E9,W6
+
+# those cause many errors, need to be fixed eventually
+ignore = F403,F405,F841