Assign default roles from config file

Add a 'default' admin set to config/default_roles.yml with the metadata manager role in it. Still need to find out what the point of having that role be optionally configured is...

If we do it this way, it would obviate the need to define the metadata manager group name in an environment variable, so there'd be some code to remove the development.env and from antsy. Also, I've only commented out some tests that would become irrelevant. Those should be removed before merging.