Enforce PEP8 empty lines

Since the current state is ambiguous, we took a vote which route to take.

@alex, @dreid, @reaperhulk, and me were all in favor of PEP8; that seems enough
of a consensus.
diff --git a/setup.cfg b/setup.cfg
index f0b8316..5d01381 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -11,6 +11,3 @@
 group = Development/Libraries
 build_script = rpm/build_script
 doc-files = doc/_build/html
-
-[flake8]
-ignore = E303