Hook up client to WMT logout
Rename LoginHandler and AuthenticationHandler

It makes more sense to swap their names.
Delete LoginAuthenticationHandler
Refresh model list on login and logout

This affects whether users can see only anonymous models or anonymous
models + their user models.
Improve code in DataTransfer

Three of the callback classes didn't implement full case statements.
Added a popup window if the case statements didn't find a match.
Set tooltips on login / logout link
Use "Email address" as label in LoginDialogBox

Use the email address as the username.
Display a QuestionDialogBox on logout from WMT

It's nicer looking than Window#confirm.
Use FA icons on login and logout

Because we like icons.