Merge branch 'develop' into blr

Conflicts:
	server/core/dcb.c
	server/modules/include/blr.h
	server/modules/routing/binlog/STATUS
	server/modules/routing/binlog/blr.c
	server/modules/routing/binlog/blr_file.c
	server/modules/routing/binlog/blr_master.c
	server/modules/routing/binlog/blr_slave.c

server/core/buffer.c

@@ -288,7 +288,11 @@ unsigned int
 gwbuf_length(GWBUF *head)
 {
 int	rval = 0;
-        CHK_GWBUF(head);
+
+	if (head)
+	{
+	        CHK_GWBUF(head);
+	}
 	while (head)
 	{
 		rval += GWBUF_LENGTH(head);