Swarm socket limit

Background details of the Swarm socket limit.

This is really the limit on the number of open file handles. Swarm has one file open per disk and a few extra handles. All the rest are sockets, so we pretty much just talk about sockets for the purposes of this support questioning.
The Swarm process has an operating system limit of 8192 file handles. The watchdog is written to poll every 15 seconds and if the Swarm process has exceeded 80% of the upper limit (6553), the watchdog reboots the box. 
The idea is to have the watchdog reboot the server before the process locks from running out of file descriptors.