feat(USRBG): update USRBG to use new API

[katlyn]

USRBG has moved storage to a new dedicated platform, allowing better integration and more control over the data that can be made available for plugins to use. This has allowed creation of a new API that has several benefits:

• The API's data is updated immediately upon a user's background being approved
• Data sent over-the-pipe can be reduced, only sending a list of user ids and a small bit of metadata (~800kB instead of the current 1.7MB)
• Dead links are no longer a possibility and do not need to be filtered out of the dataset