Add support for optparse's 'float' and 'complex' types.

This helps normalize_from_setuptools, to handle all
optparse's standard-option-types.

Fixes #452

src/flake8/options/manager.py

@@ -156,6 +156,10 @@ class Option(object):
         value = self.normalize(value)
         if self.type == "int" or self.action == "count":
             return int(value)
+        elif self.type == "float":
+            return float(value)
+        elif self.type == "complex":
+            return complex(value)
         if self.action in ("store_true", "store_false"):
             value = str(value).upper()
             if value in ("1", "T", "TRUE", "ON"):