conf: fix validation of multiple IP addresses

Previously, setting supybot.servers.http.hosts6 to multiple IP addresses always
failed because utils.net.isIPV6() gets passed a string with a space in it.
This code worked however for multiple IPv4 addresses because inet_aton(), which
is used internally by isIPV4(), allows and ignores trailing data after the
first IP address it finds.

Thanks to @MrBenC for reporting.

src/conf.py

@@ -1241,7 +1241,7 @@ registerGroup(supybot.servers, 'http')
 class IP(registry.String):
     """Value must be a valid IP."""
     def setValue(self, v):
-        if v and not utils.net.isIP(v):
+        if v and not all(map(utils.net.isIP, v.split())):
             self.error()
         else:
             registry.String.setValue(self, v)