Add converter for IP address use case

@bworrell 

This should handle the cases of parsing a flat JSON file with bot name:[list of IP addresses]

A warning in 1043a68 prompted me to use the `schemalocdict` var on stix_package, let me know if that is as intended.

Tested round-trip with sample.json | produce | consume | diff = no real changes beside newlines / ordering

I updated the docs as well