2.1.0: Merge pull request #257 from HSF/dev
(1) add options to optimize handling the database connection closed unexpected errors against postgresql
(2) add tree ordering functions (for ES)
(3) add core functions to support ES (mainly carrier and DomaPandaWork)
(4) add functions to support min_request_id (global value for idds), which will be helpful for partitioning all tables.
(5) update default idds config