Revert "Pulldown selection added for IMAP & SMTP security config"

This reverts commit 8ddbbeaffa149a06665beb0f0293635a02bf7fdf.
Dropdown selection added for IMAP & SMTP security config

(second attempt)
As discussed by the main developers of the master branch, two dropdown
boxes have been added with subsequent prefilling of the port fields.

IMAP security "none","ssl","tls"
-> IMAP port  "143","993"

SMTP security "none","ssl","tls"
-> SMTP port "25","465"

There are new challenges by adding the boxes - it breaks the original
"design". But at least the functionality is given.