Simplify initialization of replication

The users are now created on both the slaves as well as the master. This
allows static binlog coordinates to be used on the slaves and the
replication initialization boils down to a set of SQL queries.

maxscale-system-test/create_user.sh

@@ -30,4 +30,5 @@ DROP USER 'maxskysql'@'localhost';
 CREATE USER 'maxskysql'@'localhost' IDENTIFIED BY 'skysql';
 GRANT ALL ON *.* TO 'maxskysql'@'localhost' WITH GRANT OPTION;
 
+RESET MASTER;
 EOF