Add client_socket_timeout option

Add a parameter to take advantage of the new(ish) eventlet socket timeout
behaviour.  Allows closing idle client connections after a period of
time, eg:

$ time nc localhost 8776
real    1m0.063s

Setting 'client_socket_timeout = 0' means do not timeout.

DocImpact

Change-Id: If492810a2f10fa5954f8c8bb708b14be0b77fb90
Closes-bug: #1371022
Log a warning when getting lvs and vgs takes longer than 60 seconds

We know something is causing lvs/vgs commands to block while deleting a
volume and this is causing Tempest to timeout while waiting for the
volume to be deleted.  What we don't have right now is very good
(specific) logging when this happens, unless we get messages in syslog
for lvm tasks taking more than 120 seconds, but that doesn't always
happen when we see the volume delete timeout in Tempest.

This patch adds a check for when getting logical volumes and volume
groups takes longer than 60 seconds and logs a warning if that happens.
This is helpful in production also because the default interval for
periodic tasks is 60 seconds so having these take longer than that time
could cause periodic tasks to block up on each other and you'll get
warnings from the FixedIntervalLoopingCall in oslo which is controlling
the task runs.

Related-Bug: #1373513

Change-Id: I7ac5ddbbd9bda7744db33f0bb8d56879301f5538
Merge "Log a warning when getting lvs and vgs takes longer than 60 seconds"
Merge "Add client_socket_timeout option"