Make flake8/pep8 ignore perf migrations as well

setup.cfg

@@ -1,5 +1,5 @@
 [pep8]
-exclude = .git,__pycache__,.vagrant,node_modules,treeherder/model/migrations
+exclude = .git,__pycache__,.vagrant,node_modules,treeherder/model/migrations,treeherder/perf/migrations
 # E121,E123,E126,E226,E24,E704: Ignored in default pep8 config:
 # https://github.com/jcrocholl/pep8/blob/8ca030e2d8f6d377631bae69a18307fb2d051049/pep8.py#L68
 # Our additions...
@@ -11,7 +11,7 @@ max-line-length = 140
 # flake8 is a combination of pyflakes & pep8.
 # Unfortunately we have to mostly duplicate the above, since some tools use
 # pep8's config (eg autopep8) so we can't just define everything under [flake8].
-exclude = .git,__pycache__,.vagrant,node_modules,treeherder/model/migrations
+exclude = .git,__pycache__,.vagrant,node_modules,treeherder/model/migrations,treeherder/perf/migrations
 # The ignore list for pep8 above, plus our own PyFlakes addition:
 # F403: 'from module import *' used; unable to detect undefined names
 ignore = E121,E123,E125,E126,E129,E226,E24,E704,E501,F403