Garbage collector and Backend Health monitor

[aiprogMach]

This feature isn't critical for small feat usages. But for large feat app that's used heavily with so many instances and definitions, it's very useful to have Back end health monitor that can do many tasks such as:

• Detect old instances that aren't used any more and either remove them or pause them or tag them for manual processing
• Detect builds with large CPU / memory foot print and report them
  and any other reports that may be needed