Fix t/Filter_Twitter.t
Filter::Twitter: implement. some tests still fail.
Filter_Twitter: fix test so that the test for api_url option passes for filter_twitter_all(), too.
Filter_Twitter.t: fix test. Now the _transform_status_id() won't replace "https" with "http". The api_url is used as-is except for the trailing slash.
This behavior is more predictable.
Filter::Twitter: clean up comments.
Remove Input::Twitter and its tests. It is refactored into Net::Twitter::Loader and BusyBird::Filter::Twitter.