External ID for talks/series/conferences

[jamiesully]

It would be useful to add a column to talks/conferences/series that is an external ID that can be used to identify an object in another system. An external ID would allow users managing their talks via the API to cross-reference objects they own on our site with whatever external sources they are pulling from.

For example, something like a dictionary of the form external_ID = {'PIRSA': 'PIRSA:20050054', 'youtube': 'VVnTn1eHyqg'}. The keys and values wouldn't need to be unique or site-wide in our system, unless someone sees a reason for this.

The external ID could be accessible on the site to edit, or just have it exposed via the API.