Adds public cross-system BadgeClass listing

For #119.

Example of the output is here: https://gist.github.com/cmcavoy/7ad769d76c91c8832bdd

@kayelle @jpcameron can you take a look at the gist and let me know if that output is ok? 
It looks to me like the first time you hit this route, you change badgeListName to "badgelist", and all subsequent calls to showAllBadges will now send back data under "badgelist" instead of under "badges".