AwfulForumsClient is the new AwfulHTTPClient.

When we subclass framework classes for relatively trivial customization, we're
tending towards simply replacing the existing prefix with "Awful" (e.g.
AwfulNavigationController, AwfulAlertView). So one expects "AwfulHTTPClient" to
be a customized subclass of AFHTTPClient. It's not.

I also removed excessive dot notation (`[AwfulHTTPClient.client blahblahblah]`)
because Xcode's refactoring doesn't pick it up. Nor does its autocompletion.
Also it's kinda ugly?
Import into Core Data through a background managed object context.

Get that stuff off the main thread!
Update HTMLReader to 0.5.1.
Bump version to 2.0.6.
Delete pointless link from README.