LUCENE-5144: remove FacetRequest.createAggregator, rename StandardFacetsAccumulator to OldFA and move it and associated classes under o.a.l.facet.old

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1508085 13f79535-47bb-0310-9956-ffa450edef68