Unit testing, cleanup, minor schema changes.

 * created csbt_armor::get_all()
 * csbt_save::get_all_character_saves() requires characterId (arg #2)
 * csbt_save::create_character_defaults() will fail if characterId is invalid
 * updated schema so character saves & abilities are forcibly unique
 * optionally create/load character defaults in csbt_characterSheet::__construct() -- for testing
 * csbt_characterSheet::create_defaults() updated for testability
 * csbt_characterSheet::get_worn_armor() simply calls csbt_armor::get_all()
 * uncommented calls to parent::tearDown() in tests