Merge: * clients: update runtime clients of type DHCP by event from DHCP module

Close #1378

Squashed commit of the following:

commit e45e2d0e2768fe0677eee43538d381b3eaba39ca
Merge: bea8f79d 5e9c21b0
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Wed Jan 29 20:08:20 2020 +0300

    Merge remote-tracking branch 'origin/master' into 1378-dhcp-clients

commit bea8f79dd6f8f3eae87649d853917b503df29616
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Wed Jan 29 20:08:06 2020 +0300

    minor

commit 6f1da9c6ea9db5bf80acf234ffe322a4cd2d8d92
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Wed Jan 29 19:31:08 2020 +0300

    fix

commit a88b46c1ded2b460ef7f0bfbcf1b80a066edf1c1
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Wed Jan 29 12:53:22 2020 +0300

    minor

commit d2897fe0a9b726fcd97a04906e3be3d21f6b42d7
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Tue Jan 28 19:55:10 2020 +0300

    * clients: update runtime clients of type DHCP by event from DHCP module

commit 3aa352ed2372141617d77363b2f2aeaf3a7e47a0
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Tue Jan 28 19:52:08 2020 +0300

    * minor

commit f5c2291e39df4d13b9baf9aa773284890494bb0a
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Tue Jan 28 19:08:23 2020 +0300

    * clients: remove old entries of source type /etc/hosts or ARP

dnsforward/dnsforward.go

@@ -685,6 +685,7 @@ func (s *Server) handleDNSRequest(p *proxy.Proxy, d *proxy.DNSContext) error {
 		processFilteringBeforeRequest,
 		processUpstream,
 		processFilteringAfterResponse,
+		processQueryLogsAndStats,
 	}
 	for _, process := range mods {
 		r := process(ctx)
@@ -699,8 +700,6 @@ func (s *Server) handleDNSRequest(p *proxy.Proxy, d *proxy.DNSContext) error {
 	if d.Res != nil {
 		d.Res.Compress = true // some devices require DNS message compression
 	}
-
-	_ = processQueryLogsAndStats(ctx)
 	return nil
 }