text: Title: OpenAI episodes vs steps
  Body: It seems like this framework trains for N steps rather than N episodes. 
  
  When I use the env.wrapper.Monitor() to encapsulate the results for upload to OpenAI gym site, I'm getting a "can't reset a non-done environment error"
  
  ```
  Error("Tried to reset environment which is not done. While the monitor is active for {}, you cannot call reset() unless the episode is over.".format(self.env_id))
  gym.error.Error: Tried to reset environment which is not done. While the monitor is active for LunarLander-v2, you cannot call reset() unless the episode is over.
  ```
  
  Is there a way with this framework to train based on a number of episode rather than just a fixed number of steps. Using the 'nb_steps'  means that the last episode will likely be 'in-progress' when training finishes.
  
  Perhaps there's some simple setting I over looked, but I didn't see it.