Add Compatibility with Events Calendar locations for Mashup

[mathetos]

The Events Calendar is the defacto event calendar. We can add our metabox to individual events, but it has it's own location field already. I think using their location for that post type in the Mashup feature would be a much better way to go.

Feature request here:
https://secure.helpscout.net/conversation/313766264/5766/?folderId=672193