redirect success/reject logic as default in experiment.html

[Sam Zorowitz]

Basically, the idea is to make the following conditional a default in experiment.html in the MTurk/Prolific branches:

if (low_quality) {
    // Save rejected dataset to disk.
    redirect_reject("1005");
} else {
    // Save complete dataset to disk.
    redirect_success("{{workerId}}", "{{assignmentId}}", "{{hitId}}",  "{{a}}", "{{tp_a}}", "{{b}}", "{{tp_b}}", "{{c}}", "{{tp_c}}");
}

The goal would be to make more explicit the functionality of NivTurk and the choices experimenters have in how they perform rejections.