Add coverage artifacts to .gitignore

Change-Id: I786d481d23dc01d1268f1a6d7303a6c089dfdbc6
diff --git a/.gitignore b/.gitignore
index d6a7477..a2dd0a3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,9 +7,12 @@
 .testrepository
 .tox
 .venv
+.coverage
 AUTHORS
 build/*
 ChangeLog
 doc/build/*
 zuul/versioninfo
 dist/
+cover/
+htmlcov/