[ENH] Use aliases to identify the currently active index in elasticsearch, more atomic switch, better running indexer identification

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@52215 b456876b-0849-0410-b77d-98878d47e9d5
tablesorter: add latest version 2.17.6

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@52216 b456876b-0849-0410-b77d-98878d47e9d5