Java max memory should be exposed in log collector, alert engine, and collection roller

[afoerster]

This example from the Kafka project can be used as an example: https://github.com/cloudera/cm_csds/blob/master/KAFKA/src/descriptor/service.sdl#L760

Max heaps for the alert engine and collection roller should default to 2G, log collector should default to 4G.

The properties should be exported as environmental variables, and added to the java arguments in control.sh