StripDataSource

[elliottslaughter]

This PR demonstrates one possible way to strip proprietary information out of profiles. It provides an adapter for the DataSource interface that takes another DataSource and then filters all the resulting ItemMetas to redact all the string contents of those profiles. At the moment it's a pretty heavy hammer so it just strips out everything.

[elliottslaughter]

If you want something that is not quite a drastic hammer (e.g., being more specific about what gets stripped instead of taking out essentially every human-readable string), then it will probably need to be implemented at the StateDataSource level instead of as an adapter on the DataSource. But what's in this PR is definitely the fastest way to get this done.