Pulldown selection added for IMAP & SMTP security config

As discussed by the main developers of the master branch, two pulldown
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 still massive design problems with the pulldownboxes being added,
this breaks the original "design". I unfortunately don't have a clue (yet) about quickly adapting the design of the form (like aligning the port field to the right e.g.).

I somehow messed up the index.html view as I played around with copy/paste sections, but I think it only looks bad in the compare, because I didn't change anything apart adding the select and the order of the fields (port field after security field). 

p.s. This is my first commit to GitHub and to OpenSource ever, so please
be gentle :)
I don't think the text should refer to the port numbers for the security setting chosen - different systems may be configured so that 143 is actually an SSL port, or vice versa for 993 and non-SSL. While changing the security type should change the port, since those ports are the most likely for those security types, I think that the placeholder text should just remain as 'IMAP port'. The same thing applies for the SMTP port further down