Add metadata JSON per image

[imartinez]

In order to upload assets to, for example, Metaplex, you need to have one JSON file for each image metadata.
There is a similar project to this one, based on node, that builds a basic metadata JSON and lets you extend it: https://github.com/HashLips/hashlips_art_engine and

The JSON format for Metaplex is:
https://docs.metaplex.com/nft-standard

I'm planning to build this myself on top of this project. I'll open a PR as soon as I get it working.

[rounakbanik]

The library now supports creation of JSON metadata that is in compliance with standards. Please check the metadata.py file. The metadata generated should be sufficient for 90% of projects but extension is trivial should the need arise.

Closing issue.