Version 1.3.1

This is subtly different from the current default.

The default is min 256M and max of 1G, this is min and max of 1G.

> The ES_HEAP_SIZE environment variable allows to set the heap memory that will be allocated to elasticsearch java process. It will allocate the same value to both min and max values, though those can be set explicitly (not recommended) by setting ES_MIN_MEM (defaults to 256m), and ES_MAX_MEM (defaults to 1g).