[core] Adding s3 util. Common s3 functions.
[core] Adding s3 util. Common s3 functions.

openconnectome/ndlib,openconnectome/ndlib,openconnectome/ocplib,openconnectome/ocplib,neurodata/ndlib,openconnectome/ocplib,neurodata/ndlib,neurodata/ndlib,openconnectome/ndlib