open_with should be applications

[JAG-UK]

I think we've never been quite comfortable with the open_with entry other than having a firm conviction that there needs to be some way of indicating what tools or site people need to go to in order to read and use the data if it's not in an obvious format.

The Amazon Open Data metadata format has a list of applications and I think we should adopt that: application name, description and a link in each entry.