Add a network thread watchdog to look for long callbacks.
Fix how this is enabled and make the timeout configurable.
Merge pull request #997 from VoltDB/network-watchdog-hugg

Network watchdog hugg
csvloader-oom-fix: fix backport
csvloader-fix backport
Merge pull request #999 from VoltDB/csvloader-oom-fix

Csvloader oom fix
Merge pull request #1013 from VoltDB/release-3.7.0.2

Merge release 3.7.0.2 into 3.7.x branch.