T316: Fixes batch edit bug

[dolsysmith]

Fixes #316

Our override of hyrax/forms/batch_edit_form.rb added fields that are not present on all work types, which throws an error when trying to batch edit those work types.

Reverting to the original Hyrax form fixes the bug. However, use of the batch edit involves a significant caveat: the form creates a union of values in each field, so editing a field where the records in the batch have different values in that field will result in all the records getting all the same values. Batch editing should be used only when the goal is to populate all records with the same value in a given field.

If in the future we want to add fields to the batch edit form, we can patch it and append to self.terms.

Testing

1. Confirm that you can select multiple works on the dashboard and, by clicking the Edit button, open the batch editor.
2. Confirm that you can modify the value in a field and persist it by clicking Save.

[maxturer]

Reviewed this after merging my PR, and can confirm it works on my server!
Can batch edit & save and information persists.

[kerchner]

👍 Reviewed and tested. Works with both Works and ETDs, and combinations thereof. Due to the behavior noted above (it creates a union of all values in an edited field), we anyhow will only want to use this in very limited situations, and carefully at that. If we need to do more tailored batch edits, and/or batch edits involving fields unique to ETDs, Journal articles, etc., then we may want to use a script or rake task.