Liberally handle email addresses surrounded by single quotes in incoming headers

Outlook is known to produce mail headers like so:

    Cc: "John Smith" <'jsmith@example.com'>

While Mr. Smith won't have received the original mail Cc'd to him and
RT, RT can at least notify him of future mail on the ticket if
$ParseNewMessageForTicketCcs is enabled.

This commit handles incoming mail.  There are still many places that
directly parse mail headers from the database and don't strip
surrounding single quotes.  For example, headers like the above will
still produce incorrect suggestions for the "One-time Cc/Bcc" fields on
ticket reply/comment pages.  To fix this for good, we need to first
consolidate all email address/header parsing into RT::EmailParser and
then fix the problem in a single place.
Merge branch '4.0/outlook-quoted-email-addresses' into 4.0-trunk