[PATCH] circe-nickserv-handler use string-match for circe-server-network

This fixes a problem that when you connect to a network with M-x
circe, circe does not know what network it is on, therefore
auto-registering with nickserv does not work.  For example:

 M-x circe RET irc.freenode.net RET RET

Circe think the network is "irc.freenode.net", but nickserv-handler
expects it to be "freenode".

This change actually brings circe-nickserv-handler into line with the
existing documentation and definition of circe-nickserv-alist, which
says that:

NETWORK   - A regular expression matching the network or server name
---
 circe.el |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/circe.el b/circe.el
index f234ef9..4172340 100644
--- a/circe.el
+++ b/circe.el
 <at>  <at>  -2647,8 +2647,8  <at>  <at>  password for this network."
                (string= command "NOTICE"))
       (catch 'return
         (mapc (lambda (entry)
-                (when (and (string= (nth 0 entry)
-                                    circe-server-network)
+                (when (and (string-match (nth 0 entry)
+                                         circe-server-network)