Don't use cookies for login detection to avoid DDoSing AMO thanks to a recent session cookie behavior change.
Warn users about lack of cookies and private browsing windows.
Merge branch 'master' into bug-861089
Update locales.
Merge pull request #10 from kmaglione/release-1.7.2

Warn users about private mode and disabled cookies. Also merge changes pushed to AMO out of band.