before implement GraphQueryWithHistogram
working histogram
add server document level security to elastic search
Merge branch 'master' into histogram

Conflicts:
	securegraph-core/src/main/java/org/securegraph/Graph.java
	securegraph-core/src/main/java/org/securegraph/search/DefaultSearchIndex.java
	securegraph-core/src/main/java/org/securegraph/search/SearchIndex.java
	securegraph-elasticsearch/src/main/java/org/securegraph/elasticsearch/ElasticSearchGraphQuery.java