Formerly only flash 'error' was mapped to bootstrap alert 'danger' and flash keys notice and alert would require custom style or show as a blank white box. This change gives them a styled box by default, blue for notice and yellow for alert.
MySQL's default UTF-8 encoding is limited to 3-byte characters and the encoding it uses and reports for full 4-byte Unicode is called 'utf8mb4' but if the database reports this encoding, the CSV export module would try to convert string encodings utf8mb4 -> utf8. Obviously the former is not a valid encoding name in Ruby, but is actually going to be UTF-8, so this change assumes it's already UTF-8.
…uest when all of records is deleted.
…ixes #2235 Hiding a model means 'do not want to show in Navigation', so it does not prevent execution of actions.