In situations where the Gerrit server dies suddenly (not a clean
process or system shutdown, but loss of networking or an underlying
hypervisor crash), the TCP socket for the stream-events feed can be
left indefinitely hung since the client has no reason to send new
messages and will never notice that there are no further messages
arriving from the server.
Gerritlib exposes a keep alive option for Gerrit stream-events
connections which can double as a sort of dead peer detection, but
it defaults to 0 (off). Set this to 60 seconds, while allowing it to
be configured to an arbitrary value in case this is unsuitable.
Change-Id: Ib92f1ee819f060dc52163735fe8d87d6d82ab788
6fc83f806f