Todos
------
* Add notify mechanism when lost target (maybe repository structure was changed)
* Remove lxml dependency (but want to support py2.4).
* Add mercurial(hg) support.
* Add bazaar(bzr) support.
* Introduce customizable mail template.
* Attach diff without printing in the main text.(config?)
* Refactoring.
* Add test: multi url polling

Known Issues
~~~~~~~~~~~~~
* "--dry-run" update latest revision config value.

