Add ability to go back pages in sets

[lukew3]

Maybe give page a number or just show after id in bottom row. May just want to remove the back button altogether and just have a load next button. Improve buildNextUrl method so that there aren't so many cases. Should be able to use some library to generate url.

Edit: Include page number in url query params. Increment this value when moving to a new page. Maybe going back should just be simulating going back in page history.