jq type assertions on constraints

[johrstrom]

Just being on time is not enough for an event to be considered successful. This request is to add to the Constraints on the event for jq assertions.

An even could be defined as follows. Where the event must be received in 3 hours, but also should have a status field that is "finished".

<event name="onlyEvent" ok="scheduleEnd" error="email error">
    <constraints>
        <receive-by>3h</receive-by>
        <jq-assertion>.status == "finished"</jq-assertion>
    </constraints>
</event>

This particular feature should at least do == and != assertions. It could do = or ! if that's easily implementable.