Doesn't work with 1.0 compliant badges

[ottonomy]

Hey, all -- I may have time to contribute code on this in a week or two to fix this, but for the time being, this code does not work for 1.0-compliant Open Badges. It may work for some 0.5.0 badges, and it is designed to handle the badges (mis-)baked by the Issuer API in its current form. See mozilla/openbadges-backpack#1029

For 1.0-compliant badges (with a URL for the assertion's 'badge' property rather than an object representation of the Badge Class), the displayer works to extract the assertion, but fails to display any badge metadata (because all the properties intended for display are from the Badge Class)