Default service name if service name is not set on the session.

Pop service name off the session on sign out.

app/main/views/sign_out.py

@@ -8,5 +8,7 @@ from app.main import main
 @main.route('/sign-out', methods=(['GET']))
 @login_required
 def sign_out():
+    if session.get('service_name', None):
+        session.pop('service_name')
     logout_user()
     return redirect(url_for('main.index'))