Show login as menu item for staff users. Open dialog for entering username.
Initial work on getting the login_as API call to work and switch to that user
Initial working login as call.
Fixes to move network calls off main thread and sync feeds for user we have logged in as.
Hide login as menu item if isStaff has changed.
Save all/unread/focus selection across app open/close (#633)
Merge pull request #632 from manderson23/loginas

Android: Login as & #633