Update exim

When using Dovecot authentication for Exim, which is relatively common, the current regex for catching authentication failures needs a small tweak. The current plain|login options are too limiting and will only work in the cases when only the Exim's rudimentary built-in authentication is used. There can be not only the dovecot_login shown in this log example, but also dovecot_plain, ntlm, cram, cyrus, md5, and plenty of others. In fact many admins may opt for their own authentication labels, when setting up Exim. For this reason the regex should catch any label. I suggest modifying the regex in the following way:

<pre>^%(pid)s \w+ authenticator failed for (\S+ )?\(\S+\) \[<HOST>\]: 535 Incorrect authentication data( \(set_id=.*\)|: \d+ Time\(s\))?\s*$</pre>
Matching any Exim authentication name

As explained in https://github.com/grooverdan/fail2ban/pull/4, in Exim there can be used plenty of other standard authentication names, and in fact the names can be custom. The failregex in Exim filter should catch authentication errors regardless of the name of the authentication. Hence replacing the plain|login with the general \w+
Merge branch 'patch-4' of https://github.com/truxoft/fail2ban into exim-auth
Merge branch 'patch-5' of https://github.com/truxoft/fail2ban into exim-auth
Merge pull request #584 from grooverdan/exim-auth

ENH: Exim auth