EZP-23447: documented io services bc
Fix failing solr tests since travis-solr.sh switched to multi core by default
Merge pull request #1026 from ezsystems/EZP-23447-io_services_bc_doc

EZP-23447: documented io services bc
EZP-22564: first import of Elasticsearch storage
EZP-22564: fixed CS
EZP-22564: implement FieldRange visitor
EZP-22564: implement DateMetadata criterion visitors
EZP-22564: move search result extraction to handlers
EZP-22564: introduce extractor
EZP-22564: one gateway for all handlers
EZP-22564: first take on bulk indexing
EZP-22564: more responsibility for serializer
EZP-22564: rename Loader - Loading
EZP-22564: implement SectionId criterion and date sort clauses visitors
EZP-22564: remove explicit flush
EZP-22564: replace unreliable natural order ContentId sort clauses
EZP-22564: setup Travis try 1
EZP-22564: reduce number of tests
EZP-22564: separate gateway client for Solr and ES
EZP-22564: ES own gateway dependencies