Adds support for iso date string delay

[baldurh]

My company is working on adding a kue server for running jobs at particular dates in the future. To do that we need to be able to provide a date for the job via the JSON API. However, we quickly realized that the date is not recognized by kue. The reason for that is because the code uses lodash’s isDate method which only checks whether the value is a classified Date object. Dates are passed as strings via JSON so the check fails and the job is executed immediately.

This PR adds support for ISO formatted date strings by using moment.js

[behrad]

I think this can be done by the caller not inside Kue

[baldurh]

How would you do this in the caller? I did not find a way.
The problem is kue only checks if the ms variable is a JavaScript Date object which it will never be because it is always passed as a string via JSON.

[behrad]

ms is the delay interval in milliseconds, First convert your point of time in ISO string to milliseconds epoch and pass the diff from now to ms

[baldurh]

Well, the docs clearly suggest the .delay() method support passing a Date object so I was a bit surprised there was no way to use that functionality in the REST API. I just thought it was convenient since you already support it.

[behrad]

.delay classically supports ms in milliseconds however passing Date objects was added recently as a user PR. Docs may not have been updated accordingly :)