Renamed the bobrc variables and update the docs

Hey,

• I've changed the name of the rc variables.
• Set the download method to save the model path in the rc variable
• Added documentation saying how to reset this value

Closes #2 (closed)

I am not sure automatically downloading something and adding it to the users rc is a good idea. Also, _saverc is private API and your code could break anytime.

However, this is not end of the world either.

Well, shall we prompt this information?

I would have preferred that you saved this inside the home folder of the user. For example ~/.bob/bob.ip.tensorflow_extractor/facenet_model. This way it would not be deleted if the conda environment is deleted. We even could have a storage folder for bob that can be customized using bob config set .... What do you think?

I will tackle that after bob.extension#50 (closed)

enabled an automatic merge when the pipeline for d67d354f succeeds

mentioned in issue bob.extension#52 (closed)

merged

mentioned in commit ff0a629f