Make mesh dump optional

[gshipman]

This is painful at larger mesh sizes, please consider making this optional:

index b1f0fd0..e51c639 100644
--- a/apps/hydro/driver.h
+++ b/apps/hydro/driver.h
@@ -232,9 +232,9 @@ int driver(int argc, char** argv)
 
 
   // dump connectivity
-  auto name = flecsi_sp::utils::to_char_array( inputs_t::prefix+".txt" );
-  auto f = flecsi_execute_task(print, apps::hydro, index, mesh, name);
-  f.wait();
+  //auto name = flecsi_sp::utils::to_char_array( inputs_t::prefix+".txt" );
+  //auto f = flecsi_execute_task(print, apps::hydro, index, mesh, name);
+  //f.wait();
 
   // start a clock
   auto tstart = ristra::utils::get_wall_time();