Cleanup comments and class names s/ElasticSearch/Elasticsearch

 * Clean up s/ElasticSearch/Elasticsearch on docs/*
 * Clean up s/ElasticSearch/Elasticsearch on src/* bin/* & pom.xml
 * Clean up s/ElasticSearch/Elasticsearch on NOTICE.txt and README.textile

Closes #4634
Fix ASL Header in source files to reflect s/ElasticSearch/Elasticsearch

This commit also removes the license to Shay Banon in favor of soley
Elasticsearch. Thanks Shay for this awesome product you took it far!

Closes #4636
Add missing license headers