Add dump pickle method for environments

[jamescasbon]

Some environments are not suited to video encoding methods. This PR allows coach to just pickle the environment render responses so that you can use them for analysis.

[jamescasbon]

I can redo the documentation if you are willing to accept.

It makes the review process quite hard if you churn the docs as well.

[jamescasbon]

Hi all, what do you think? Its a pretty simple change.

[gal-leibovich]

Hi @jamescasbon, sorry for delaying with the response.

The functionality seems good to me. Which environments have you encountered that their rendering is not supported for video encoding or GIFs creation?

Also, now with #326, creating the documentation is very easy, and does not require you to have all the environments installed. #326 should be merged to master soon.

[jamescasbon]

The functionality seems good to me. Which environments have you encountered that their rendering is not supported for video encoding or GIFs creation?

I have custom environments where I'd much rather get the raw data out for post processing. Maybe the raw data is recoverable from the other methods but it seemed like mp4 would be compressed.