Force schedule snapshot task on bucket creation

Because we de-duplicate the snapshot task scheduling, it
is possible that a
Delete,Create gets re-ordered as Create,Delete because the
first create task was de-duplicated but the actual task runs
before the Delete task

Change-Id: I2d617ff2a63d4a6ff592ee03f883d5a9e75fd588
Reviewed-on: http://review.couchbase.org/36300
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: abhinav dangeti <abhinav@couchbase.com>