Bug 1062829 - Converted Json methods from XHR to LazyLoader in the FTU A...

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https://bugzilla.mozilla.org/show_bug.cgi?id=1062829
I'm unclear if this will be async or not now. If we stub LazyLoader.getJSON to return a resolved promise with our mockConfig output, doesnt that mean this whole block is sync? In which case we should get rid of the done() callbacks. Either way a comment here would be good. Sorry to labor the point, but understanding and fixing somone else's async tests is one of the hardest things we do :)