Java heap size defaults

[daytimeforninja]

We have found multiple installations where the aggregate heap size of all running java processes is larger the the extant physical memory on the machine. It is a common enough antipattern to require a xxx check. It would be nice if there were a required heap size default in the sls spec so xxx would have the ability to more intelligently recommend service placement without the need to rely on javaOpts, which is frequently not set.