Fixing unit tests to wait for persistence in order to test with stale=false

Change-Id: I5fbbfa5121f6ce7bc61c00a1a25c9a321c7115bf
Reviewed-on: http://review.couchbase.org/24151
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>