sympl-mail: replace old SMTP/POP/IMAP testing functionality
# test.d/tc_dovecot.rb
## IMAP
- [x] test_imap_capabilities - check capabilities for IMAP4REV1, AUTH=PLAIN, AUTH=LOGIN and STARTTLS.
- [x] test_imap_auth_plain - login with PLAIN auth
- [x] test_imap_auth_plain_local_user - login with PLAIN auth with a local user
- [x] test_imap_auth_login - login with LOGIN auth
- [x] test_imap_auth_login_crypt - login with LOGIN auth and crypt'd password
- [x] test_imap_auth_starttls - STARTTLS session
- [x] :exclamation: test_imap_auth_ssl - LOGIN auth with STARTTLS
## POP3
- [x] test_pop3_auth - direct POP3
- [x] :exclamation: test_pop3_auth_crypt - crypt'd password
- [x] test_pop3_auth_tls - "not implemented by net/pop library", probably test STARTTLS
- [x] :exclamation: test_pop3_auth_ssl - crypt'd password via SSL
## SMTP
- [x] test_deliver - test delivery to mailbox
- [x] test_deliver_local_user - test delivery to local user
- [x] test_imap_quotas - mailbox quota via imap
- [x] test_deliver_with_quotas - mailbox quota smtp
- [x] test_deliver_with_sieve - sieve delivery
- [x] test_deliver_with_sieve_for_local_users - sieve delivery for local user
- [x] test_deliver_with_sieve_and_quota - sieve delivery for local user with quota
# test.d/tc_exim4_live.rb
## AUTH
- [x] test_smtp_capabilities - on public_ip:25, check STARTTLS, AUTH PLAIN, AUTH LOGIN are not offered. on localhost:25, check AUTH PLAIN and AUTH LOGIN are not offered, enable STARTTLS, check AUTH PLAIN and AUTH LOGIN are offered
- [x] test_smtp_auth - AUTH PLAIN/LOGIN for plaintext pass
- [x] test_smtp_auth_local_user AUTH PLAIN/LOGIN for local user
- [x] :exclamation: test_smtp_auth_crypt - AUTH plain test for regular/start_tls
- [x] test_ratelimiting - send 3 mails, set rate limit 1000000, send one more, drop limit to 1, send 3 messages (should fail), change limit to 100, send message (should succeed), check mail spool
issue