Nest Ingredient Observers Inside Main Experiment Directory

[decodyng]

This PR:

• Creates a "nest_ingredients" parameter on Experiment object
• Passes the list of ingredients into the Run object created within experiment
• For runs with a FileStorageObserver attached, and with the nest_ingredients flag set to true, iterate over ingredients and add to that ingredient a FileStorageObserver with a directory at /<ingredient_name> .

[AdamGleave]

More Pythonic: isinstance(observer, FileStorageObserver). That will also match subclasses, which is probably desirable, but if not can do observer.__class__ ==FileStorageObserver.

[AdamGleave]

Minor comment