ObjectColumnSelector/JS aggregator support for multi-valued columns.
JavaScriptAggregator: Context.newArray makes nicer arrays than Context.javaToJS.
More consistent ObjectColumnSelectors. JS aggregator tests for nulls.
More JS aggregator tests.
JavaScriptAggregator comment explaining why primitive wrapping is anti-helpful.
add JavascriptAggregatorBenchmark
Merge pull request #546 from metamx/object-column-selector-multivalued

ObjectColumnSelector/JS aggregator support for multi-valued columns.