Remove instances in the queue

[melinath]

The readme states:

deletes have to be handled in line (otherwise the instance cannot be looked up when they are pulled off the queue)

However, this is not the case. Instances can easily be removed by passing a string of the form "<app_label>.<model_name>." to the haystack backend. You can see an example of this here.

[sdcooke]

Didn't spot that when I wrote this - feel free to add it.