DatabaseSchema: several changes
DatabaseSchema: several changes

 - Fix typo in SQL.
 - Use 'NOT NULL'.
 - Use transactional DDL.
 - Fix version number in "upgraded to X" string.

freedesktop-unofficial-mirror/zeitgeist__zeitgeist,freedesktop-unofficial-mirror/zeitgeist__zeitgeist,freedesktop-unofficial-mirror/zeitgeist__zeitgeist,freedesktop-unofficial-mirror/zeitgeist__zeitgeist,freedesktop-unofficial-mirror/zeitgeist__zeitgeist