text: Title: keyerror ONLINE_LAST_MINUTES
  Body: I clone the repo and follow the doc to deploy my flaskbb, but when I run command :
  python manage.py createall
  it hints not found the command , so I use command "python manage.py initdb" instead
  
  I also do the command :
  cp flaskbb/configs/production.py.example flaskbb/configs/production.py
  but when run:
  python manage.py runserver
  it hints keyerror:
  
  Traceback (most recent call last):
    File "/Users/xiaobing/workspace/flask_apps/venv/lib/python2.7/site-packages/flask/app.py", line 1836, in **call**
      return self.wsgi_app(environ, start_response)
    File "/Users/xiaobing/workspace/flask_apps/venv/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
      response = self.make_response(self.handle_exception(e))
    File "/Users/xiaobing/workspace/flask_apps/venv/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
      reraise(exc_type, exc_value, tb)
    File "/Users/xiaobing/workspace/flask_apps/venv/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
      response = self.full_dispatch_request()
    File "/Users/xiaobing/workspace/flask_apps/venv/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
      rv = self.handle_user_exception(e)
    File "/Users/xiaobing/workspace/flask_apps/venv/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
      reraise(exc_type, exc_value, tb)
    File "/Users/xiaobing/workspace/flask_apps/venv/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
      rv = self.dispatch_request()
    File "/Users/xiaobing/workspace/flask_apps/venv/lib/python2.7/site-packages/flask_debugtoolbar/**init**.py", line 124, in dispatch_request
      return view_func(**req.view_args)
    File "/Users/xiaobing/workspace/flask_apps/flaskbb/flaskbb/forum/views.py", line 47, in index
      online_users = User.query.filter(User.lastseen >= time_diff()).count()
    File "/Users/xiaobing/workspace/flask_apps/flaskbb/flaskbb/utils/helpers.py", line 296, in time_diff
      diff = now - timedelta(minutes=flaskbb_config['ONLINE_LAST_MINUTES'])
    File "/Users/xiaobing/workspace/flask_apps/flaskbb/flaskbb/utils/settings.py", line 26, in **getitem**
      return Setting.as_dict()[key]
  KeyError: 'ONLINE_LAST_MINUTES'
  