Add W504 and standard ignores

This updates setup.cfg's flake8 config to match the template
https://github.com/lsst/templates/blob/master/project_templates/stack_package/example/setup.cfg
which includes the new W504, and also a standized set of exclusions that
covers what was already excluded

setup.cfg

@@ -4,9 +4,16 @@
 # if there are later changes to the developer guide standard.
 [flake8]
 max-line-length = 110
-ignore = E133, E226, E228, N802, N803, N806
-exclude = __init__.py, testLib.py, ticket1914.py
+ignore = E133, E226, E228, N802, N803, N806, W504
+exclude =
+  bin,
+  doc,
+  **/*/__init__.py,
+  **/*/version.py,
+  tests/.tests,
+  testLib.py,
+  ticket1914.py
 
 [tool:pytest]
 addopts = --flake8
-flake8-ignore = E133 E226 E228 N802 N803 N806
+flake8-ignore = E133 E226 E228 N802 N803 N806 W504