Load More Pull Request per Chris Bibby

A small browser extension to assist with reviewing Github Pull Requests. An additional button is added to the PR tool bar when reviewing a pull request that will load multiple file diffs at a time - no more having to click each of the 'Load diff' links.

The extension is limited to loading 25 diffs at a time and clicking it is only allowed once every 5 secs - these measures are to help prevent being throttled/blocked by Github.