MB-9904: setVBucketState API for UPR

Change-Id: I1bf38c06f042beb570b7cfceb2acde2240858916
Reviewed-on: http://review.couchbase.org/32615
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>