timeline.js: StatusesSummary: only shows 'this_count' for the top-level status count, because 'this_count' and 'above_count' is always the same.
Test::StatusStorage: add tests to 'common' suite to check if the given storage can accept Unicode timeline names and status IDs. PODs are updated so that it clearly states status IDs and timeline names should be Unicode strings.
StatusStorage::SQLite: set 'sqlite_unicode' option so that it can handle Unicode status IDs. Now that SQLite DB can accept Perl's Unicode strings, to_json() and from_json() are used instead of encode_json() and decode_json(), respectively.