Extension:CentralNotice/cn known mobile carriers table

Schema summary
mysql> describe cn_known_mobile_carriers; +--++--+-+-++ +--++--+-+-++ +--++--+-+-++
 * Field           | Type           | Null | Key | Default | Extra          |
 * mc_id           | int(11)        | NO   | PRI | NULL    | auto_increment |
 * mc_name         | varbinary(255) | NO   | MUL | NULL    |                |
 * mc_display_label | varbinary(255) | NO  |     | NULL    |                |