Updating Article's metadata datastream

Matching Notre Dame's defined Metadata Application profile for
Article. See:

http://ndlib.github.io/metadata_application_profile/templates/

@WIP - This is a work in progress. The purpose of this commit is a
reference for updates against Article. This will impact the migration
scheme.

[skip ci]
Renaming :journal_information to :source

This appears to be the only required changes for user facing data.

[skip ci]
Removing identifier and date_digitized

[skip ci]
Rearranging the migration runner

[skip ci]
Adding initial migration script

[skip ci]
Writing transformer for metadata
Including MetadataNormalization cap task
Updating matchers to be discoverable

I want `require 'curate/spec_support'` to function in applications
that mount the Curate engine.

[skip ci]
Exposing Article attributes to form
Working on migration script for Article
Adjusting how transformer is called
Refactoring: extracting methods
Updating viewer attributes
Updating metadata transformer