- change managesieve_mbox_encoding to UTF-8 in .dist config according to RFC

plugins/managesieve/config.inc.php.dist

@@ -17,8 +17,8 @@ $rcmail_config['managesieve_default'] = '/etc/dovecot/sieve/global';
 
 // Sieve RFC says that we should use UTF-8 endcoding for mailbox names,
 // but some implementations does not covert UTF-8 to modified UTF-7.
-// Defaults to UTF7-IMAP for backward compatybility
-$rcmail_config['managesieve_mbox_encoding'] = 'UTF7-IMAP';
+// Defaults to UTF7-IMAP
+$rcmail_config['managesieve_mbox_encoding'] = 'UTF-8';
 
 // I need this because my dovecot (with listescape plugin) uses
 // ':' delimiter, but creates folders with dot delimiter