Default mem calc strategy should be "rss"

This is due to a scenario in which the Erlang VM allocator stats report a huge increase in memory consumption which is only reflected in VSS increase, not RSS

PT #152081051

Author: lukebakken

Makefile

@@ -16,7 +16,7 @@ define PROJECT_ENV
 	    {ssl_options, []},
 	    {vm_memory_high_watermark, 0.4},
 	    {vm_memory_high_watermark_paging_ratio, 0.5},
-	    {vm_memory_calculation_strategy, allocated},
+	    {vm_memory_calculation_strategy, rss},
 	    {memory_monitor_interval, 2500},
 	    {disk_free_limit, 50000000}, %% 50MB
 	    {msg_store_index_module, rabbit_msg_store_ets_index},