Make the logout button on the spotify settings page actually work

src/internet/spotifyservice.cpp

@@ -639,4 +639,8 @@ void SpotifyService::Logout() {
   blob_process_ = NULL;
 
   login_state_ = LoginState_OtherError;
+
+  QSettings s;
+  s.beginGroup(kSettingsGroup);
+  s.setValue("login_state", login_state_);
 }

src/internet/spotifysettingspage.cpp

@@ -152,4 +152,6 @@ void SpotifySettingsPage::UpdateLoginState() {
 void SpotifySettingsPage::Logout() {
   service_->Logout();
   UpdateLoginState();
+
+  ui_->username->clear();
 }