Check if queue exists before sending the message

[mrister]

New Feature

On producer, check if a queue exists before sending the message and reject produce function if it does not not.

Currently:

 producer.produce('non existent queue',  { msg: Date.now() }, {rpc:true}).then(...)

Waits indefinitely or resolves immediately in case rpc: false for a queue that does not exists.

Acceptance

Check if the queue exists before sending the message and if not, reject the produce function with an appropriate error denoting that the queue does not exist.