InvalidCastException while binding on a ListView

I'm trying to make a ListView on a page and Xamarin.Forms throws an InvalidCastException. I've no idea why.

Code: https://gist.github.com/JohnACarruthers/424b5e0bdeb5cc022829

The exception copy/pasted from Xamarin Studio is included as the last file in the gist.

Any insight on why I'm getting the exception would be appreciated.