Improve status API performance

[jbornemann]

Grabbit is computing status by fetching, and iterating through structures in an n+1 problem sort of manner. O(n^2) from quick observation. No caching/memoization.

As a good first step, we need :

1.) var/grabbit JCR indexing, but keeping in mind that we don't want indexing of volitile, active write persistence - as this will cause reindexing churn.
2.) Favor JCR queries over programmatic resource iteration

[jbornemann]

@jdigger @sagarsane per our discussions. Feel free to add more detail