load client configuration async
Fix up the `this` scope problems.
Simplify consumers of the FxaClientWrapper by depending on promises.

* Clients no longer have to call getAsync() to get a client. We do that for them.
This is how I though promises should work, everything in a waterfall.
add the missing return
refactor promises
Merge pull request #283 from mozilla/reconfig-how-it-should-be

Reconfig how it should be