Increase timeouts for tests

bug507 and bug519 had relatively low timeouts which seem to be triggered
quite often.

maxscale-system-test/bug507.cpp

@@ -65,7 +65,7 @@ const char * sel1 = "select last_insert_id(), @@server_id";
 int main(int argc, char *argv[])
 {
     TestConnections * Test = new TestConnections(argc, argv);
-    Test->set_timeout(10);
+    Test->set_timeout(60);
 
     Test->repl->connect();
     Test->connect_maxscale();