Clean up the temp table space when queries finish; Clean up the memory when aggregation finishes
Merge pull request #1675 from VoltDB/ENG-6888-temp-table

ENG-6888. Backport to 4.0.1.x.
Set Version 4.0.1.4
do not purge on the serial aggregation finish phase, because of the scop pointer stuff; anyway, there is no much memory usage in serial aggregation.
ENG-6915: When connecting a new client in the JDBC driver, call
close() on the client if it doesn't connect to the cluster to avoid
leaking threads.
(cherry picked from commit 2db97d460251134edeb3d51cca264a4b9c79383c)
ENG-6910. ant support for making a customized buildstring.txt.
Setting -Dbuildstring="string" will save the derived buildstring.txt
to altbuildstring.txt and overwrite the contents.
Merge pull request #1677 from VoltDB/release-4.0.1.x-upgrade-compatible

Release 4.0.1.x upgrade compatible