Add option for dynamic memory detection to batch launch scripts

[Kevin Milner]

Currently our shell script writers require a single amount of memory, but we often run jobs on mixed computing environments. For example, the SCEC queue at USC HPCC has machines with 12 and 42 GB of memory. Some calculations (ETAS) can make use of additional memory to run faster, but will run fine on lower memory systems. Our launch scripts should detect system memory reliably and adjust the JVM maximum memory statement when required (this will be optional and not the default behavior).

[Kevin Milner]

Done in [10851]. You can now call JavaShellScriptWriter?.setAutoMemDetect(true) to enable this feature. It can only increase memory above the regularly specified limit, and won't increase to more that 3GB under the total system memory.