JCBC-227: Implementing backoff on resubscribe thread.

This changeset implements a backoff algorithm when resubscription
is needed and no valid node can be picked up from the list. Each
try waits 1 second longer (from 0), up to 10 second max. It will
loop until a valid configuration can be picked up.

Change-Id: Ia5be1e74e16c5692d5a94a9df3ec366de3c0aaf0
Reviewed-on: http://review.couchbase.org/24322
Reviewed-by: Matt Ingenthron <matt@couchbase.com>
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>