Move date and time formats to 'constants' module
Rename name_attribute to label_attribute
Remove support for passing in a URI to origins.connect

This method is more limited and more difficult to construct than simply
passing in parameters.

Also removed other unused utilities.
Ensure the public node source is available prior to augmenting the key
Synchronize nodes on initialization

This is a temporary fix until a lazy method is introduced.
Add chinook test data Excel, CSV, Mongo, and PostgreSQL
Add rudimentary backend for MySQL