Fix #1158: Allow mail addresses with different full names

As stated in http://www.sogo.nu/bugs/view.php?id=1158, the the MailFieldNames fields (like _mail_) can only contain a plain E-Mail address, without a full name like _"Dude" \<bro@example.com\>_. If the value contains never the less a full value, something strange happened:
* Since SOGo 2.2.1: The result would have been _"Bro" \<"Dude" \<bro@example.com\>\>_
* Before SOGo 2.2.1: The result would have been _"Bro" \<bro@example.com\>_
therefore the only sane values have been without a full name and "<>".

Now it is possible to have
* E-Mail addresses without a full name
* E-Mail addresses with a different full name

to accomplish this, without breaking backward compatibility for former sane configurations, the new behavior only kicks in if the value contains a "<". Depending on it's position, one of the two new E-Mails address types is selected. The mapping is as following:

| Input | Result | Users fullName |
|---:|---:|:---:|
| bro@example.com | "Bro" \<bro@example.com\> | "Bro" |
| bro@example.com | bro@example.com | "" |
| \<bro@example.com\> | bro@example.com | "Bro" or "" |
| "Dude" \<bro@example.com\> | "Dude" \<bro@example.com\> | "Bro" or "" |