fix defaults for relx template

priv/templates/relx_rebar.config.dtl

@@ -14,7 +14,7 @@
         {extended_start_script, true}]
 }.
 
-{profiles, [{prod, [{relx, [{dev_mode, true},
-                            {include_erts, false}]}]
+{profiles, [{prod, [{relx, [{dev_mode, false},
+                            {include_erts, true}]}]
             }]
 }.