Handle authentication errors after password change

WriteDetailTask and NetworkTask now have a callback if there is an
authentication error (HTTP status 401). These callbacks are handled in
Home and DetailView.
Now if the user changed his password and does something within the app
that requires authentication a dialog is shown asking for the new
password.
Changes for latest switch to AccountManager
Use AuthenticationCheckTask in FirstTimeInit

This removes the networkThread and the messenger-Handler.
Automatic code reformat as suggested by @ratan12
Merge pull request #205 from d-sko/auth_fix

Handle password changes