MXS-1300: Test calling of module commands via MaxCtrl

The calling of module commands is tested by using the qlafilter log
command.

test/maxscale_test.cnf

@@ -49,6 +49,7 @@ router_options=master
 servers=server1
 user=maxuser
 passwd=maxpwd
+filters=QLA
 
 [Hint]
 type=filter
@@ -69,6 +70,14 @@ type=filter
 module=tee
 service=RW Split Hint Router
 
+[QLA]
+type=filter
+module=qlafilter
+log_type=unified
+append=false
+flush=true
+filebase=/tmp/qla.log
+
 [CLI]
 type=service
 router=cli