listAndGet, getBulk

• listAndGet will list files in a folder and get all of them
• getBulk takes in an array of s3 Keys and will get all of them

return json when appropriate and support fallback

put and get will write/read JSON when passed a json object. get now has a fallback option so that if the S3 Object is not found, it will return the fallback instead of throwing an error.

version 1

First working version, works on both s3 and locally. See tests for example usage.