Allow specifying max heap size from env #8

Job	Run time
ci / Build	5m 50s
ci / Lint	1m 7s
ci / Test (0)	5m 22s
ci / Test (1)	7m 14s
ci / Test (2)	7m 30s
ci / Test (3)	4m 58s
ci / Test (4)	4m 23s
ci / Test (5)	6m 13s
ci / Test (6)	5m 54s
ci / Test (7)	8m 27s
ci / Test (8)	6m 35s
ci / Test (9)	5m 56s
ci / Publish Unit Tests Results	1s
	1h 9m 30s

Provide feedback