Merge pull request #621 from nelenkov/dev

temporarily disable revnue fetching, see #620
Merge pull request #629 from nelenkov/dev

Parse revenue from statistics endpoint, see #620
Don't fail if UserDetails does not have a preferred currency
Merge pull request #630 from willlunniss/find-preferred-currency-fix

Don't fail if UserDetails does not have a preferred currency
use per-account namespace for AdSense, see #628