Added functionality for Java Native Memory Tracking to new helper - nmt

[pivotal-david-osullivan]

Summary

This PR adds Java Native Memory Tracking (NMT) features as part of RFC0003.
A helper has been added which sets the following required variables/flags to configure Java NMT:

• "NMT_LEVEL_1=summary" - required to enable NMT successfully due to JDK bug
• "-XX:+UnlockDiagnosticVMOptions"
• "-XX:NativeMemoryTracking=summary" - (summary report of memory usage)
• "-XX:+PrintNMTStatistics" - (prints memory usage data at VM exit)

These features will be enabled by default but come with a small amount of overhead - to disable Java NMT, users can set BPL_JAVA_NMT_ENABLED=false at runtime.

Use Cases

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).

[dmikusa]

Looks good, that one minor note.