Create CSV cache

[andyblarblar]

Using the API access lib, create a class that abstracts over a cache of the API. This class would take a path to a directory as an argument, and check the cache in that directory. Using the DB access lib, it will ensure that cache is complete. The cache should have the following layout:

• db.csv: A CSV file with a table esk layout, linking pattern IDs and metadata
• assets/{pattern id}: A directory of directories, where each subdirectory is named after a pattern ID. Inside of these directories are all images of that id. These images should be named patternid-center.jpg and so on for each image.

This will be used in the training process, to both train the model and generate an embeddings store.

[wyliew19]

Updated to JSON cache (later will be parquet if space or speed becomes concern)