Feature request: cache results

[XioNoX]

It would be useful to be able to locally cache the results, for at least --list and possibly --host.

With a variable like "refresh_cache:" (1d, 1h, etc...) in netbox.yml to download fresh data once in a while.
As well as a netbox.py --refresh-cache option to force the download of fresh data.

Similar to http://docs.ansible.com/ansible/latest/user_guide/intro_dynamic_inventory.html#refresh-the-cache