Add push to front of rate limit queue.

[dceejay]

(moved random delay to top to group with other delay types.
Tests and docs to follow

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Proposed changes

This adds (allows) a msg.lifo property . If it exists on a msg for a rate limited queue then it adds it to the front of the queue (unshift) rather than the end so it will be first out (Last In First Out).

This allow building a stack type queue if required - or a push back in case of failure retry type queue.

• Add tests
• Enhance Docs

Checklist

• I have read the contribution guidelines
• For non-bugfix PRs, I have discussed this change on the forum/slack team.
• I have run grunt to verify the unit tests pass
• I have added suitable unit tests to cover the new/changed functionality

[coveralls]

Coverage increased (+0.07%) to 67.662% when pulling ef1b3aa on delay-push-to-front into 66a704a on dev.

[knolleary]

I can see the value in this - my only concern is msg.lifo is not a very accessible property name, particular when you consider non-English speaking users.

In my mind lifo is like rbe - a technical term that will be familiar to those that know, but not intuitive to those unfamiliar.

If we can think of a better name, then we could get this into 2.0 - otherwise it'll have to wait.

[dceejay]

How about msg.pushback ?
Or. msg.toFront ?

[dceejay]

/easycla