agent, broker, lib: less logging at INFO level

Decrease the amount of output going to the logs at INFO level.
Accomplished via:
 - moving some logging calls from INFO to DEBUG
 - log agent metadata only occasionally or when changed
 - fix the log filter which assists intermittent logging
 - apply said filter to additional log statements to silence some
   redundant updates

Also double retention to 8 log files rather than 4.

Change-Id: I8b4614a6ea23c2813c0341e03171328e24f148c8
Bug-Url: https://bugzilla.redhat.com/1019471
Signed-off-by: Greg Padgett <gpadgett@redhat.com>