Stabiltiy Timestamp Persistence
Persist statbility in gometa such that it can be used for coordinator
failover as well as bootstrap.  Timer will initialize based on
stability timestamp stored in gometa.

Change-Id: I025f589edbdb7a84f2144f1cf0bc4f3d6c022cc8
Reviewed-on: http://review.couchbase.org/43938
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Reviewed-by: John Liang <johliang00@gmail.com>
Tested-by: John Liang <johliang00@gmail.com>