Fixes #14 and #19.

@BackSeat contributed the patch. Signature changes are mentioned in README.

flake8/util.py

@@ -3,8 +3,10 @@ import re
 import os
 
 
-def skip_warning(warning):
+def skip_warning(warning, ignore=[]):
     # XXX quick dirty hack, just need to keep the line in the warning
+    if warning.message.split()[0] in ignore:
+        return True
     if not os.path.isfile(warning.filename):
         return False