Don't record and use TTP/TTR from observe

Just poll at a fixed interval, as the
responses from the server side can be unreliable

Change-Id: I919eb1d5262fc01747ebd4f723589c333572cf3b
Reviewed-on: http://review.couchbase.org/28975
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Brett Lawson <brett19@gmail.com>