Wait after logout() in account_settings tests (bug 1020262)

That wasn't necessary before, but in e5aa1399 we introduced a new
API call for logout, so it's not done instantaneously.
Wait till we see the buttons that show up when logged out (bug 1020262)
add "Back to app" link from reviews list page (bug 872880)
Fix another test by waiting on something relevant for logout (bug 1020262)
Indicate whether applications support offline (bug 861303)
Merge pull request #473 from cvan/back-to-app

add "Back to app" link from reviews list page (bug 872880)
Merge pull request #468 from diox/expose-offline

Indicate whether applications support offline (bug 861303)
Remove position: relative on ratings now that install is floating (bug 1021719)

(It's preventing clicks on the install button)