Correct issue with BucketManager flush method.
Correct issue with BucketManager flush method.

Change-Id: I4baa698ec25cba619a1d51f4df8e44e697d26d1a
Reviewed-on: http://review.couchbase.org/62660
Reviewed-by: Mark Nunberg <dab05a0fe859c5cb93882b2a75a0d613501b07be@couchbase.com>
Tested-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>

brett19/gocb