LUCENE-4607: add DISI/Spans.cost

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1456670 13f79535-47bb-0310-9956-ffa450edef68
SOLR-4574: The Collections API will silently return success on an unknown ACTION parameter.
SOLR-4576: Collections API validation errors should cause an exception on clients and otherwise act as validation errors with the Core Admin API.
SOLR-4577: The collections API should return responses (success or failure) for each node it attempts to work with. 

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1456683 13f79535-47bb-0310-9956-ffa450edef68