hudmol/archivesspace — pull request #685 by payten (2014-02-12 09:52:05+00:00)
Title: Make external documents a simple one-to-many nested record

Add migration to convert the external document many-to-many relationship to a one-to-one.

Modify the external document mixin to define a basic one-to-many nested record.

Clean up the unique location (within a record) validations and add a translation (it was without an error msg at all).