* Changes for lookup synchronization
* Refactor of Lookup classes
* Minor refactors and doc update
* Change coordinator instance to be retrieved by DruidLeaderClient
* Wait before thread shutdown
* Make disablelookups flag true by default
* Update docs
* Rename flag
* Move executorservice shutdown to finally block
* Update LookupConfig
* Refactoring and doc changes
* Remove lookup config constructor
* Revert Lookupconfig constructor changes
* Add tests to LookupConfig
* Make executorservice local
* Update LRM
* Move ListeningScheduledExecutorService to ExecutorCompletionService
* Move exception to outer block
* Remove check to see future is done
* Remove unnecessary assignment
* Add logging