meta_data(+Dict, -Meta, +Options) is det[private]
 meta_data(+Store, +Dict, -PrevMeta, -Meta, +Options) is det[private]
Gather meta-data from the Request (user, peer, identity) and provided meta-data. Illegal and unknown values are ignored.

The meta_data/5 version is used to add information about a fork.

Arguments:
Dict- represents the JSON document posted and contains the content (data) and meta data (meta).