adding scenario for creating a new api key for an existing marketplace

[steveklabnik]

This looks good. Should we pull that schema out into a real fixture?

[matthewfl]

I just copy and pasted what was there for the other api key without really thinking. Both of these secnarios should be using an api schema, and I believe that we already have one, let me change that

[matthewfl]

apparently we do not have an api schema, so I am going to create one and add it to this pr

[steveklabnik]

I think last time we said "we should probably refactor this into a real schema."

No time like the present!

[remear]

Updates?