Support SSL for IMAP authentication

Based on Nikita Koshikov's commit:
https://github.com/interlegis/Radicale/commit/000fc2a

config

@@ -38,7 +38,7 @@ stock = utf-8
 
 [auth]
 # Authentication method
-# Value: None | htpasswd | LDAP | PAM | courier
+# Value: None | htpasswd | IMAP | LDAP | PAM | courier
 type = None
 
 # Usernames used for public collections, separated by a comma
@@ -71,6 +71,11 @@ ldap_password =
 # LDAP scope of the search
 ldap_scope = OneLevel
 
+# IMAP Configuration
+imap_hostname = localhost
+imap_port = 143
+imap_ssl = False
+
 # PAM group user should be member of
 pam_group_membership =