 + comments from matt smart:    change the address exclusion error to RunTimeError    exception docstrings    typo in docstring.
 + comments from matt smart:
   change the address exclusion error to RunTimeError
   exception docstrings
   typo in docstring.

git-svn-id: ff1bd20d4810c92495c9b7b1169b6cc20646d37a@127 09200d28-7f98-11dd-ad27-0f66e57d2035

JonathonReinhart/ipaddr-py,JonathonReinhart/ipaddr-py