[Web] Adjust mailbox format

[Web] Include IMAP lib for future use
[Web] Fix default exception handler
[Web] Fix sync job edit forms
[Web] Other minor fixes

data/web/inc/lib/composer.json

@@ -4,6 +4,7 @@
         "yubico/u2flib-server": "^1.0",
         "phpmailer/phpmailer": "^5.2",
         "php-mime-mail-parser/php-mime-mail-parser": "^2.9",
-        "soundasleep/html2text": "^0.5.0"
+        "soundasleep/html2text": "^0.5.0",
+        "ddeboer/imap": "^1.5"
     }
 }