Add a way of generating a list of pull requests to look at.

Feature request by greenman, we need a way to generate a list of pull requests which require attention.

This should be configurable to show things such as X number of pull requests that have had the longest time since last response. It should also have an option to show Y number of new pull requests that have not had a response in Z days.

There are likely more reports we will want to generate from this.